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Jaring jaring Kubus

Sebuah kubus apabila dipotong menurut rusuk-rusuknya kemudian tiap sisinya direntangkan akan menghasilkan jaring-jaring kubus.
Jaring-jaring kubus terdiri dari enam buah persegi kongruen yang saling berhubungan. Berikut animasi jaring-jaring kubus :

Irjen Gandeng KPK Telusuri Mandeknya Dana Sertifikasi Guru

JAKARTA - Tim khusus yang dibentuk Inspektorat Jenderal Kemendikbud, yang melibatkan Komisi Pemberantasan Korupsi (KPK), masih melakukan kajian terhadap mandeknya penyaluran dana tunjangan sertifikasi guru. Tim ini sudah mulai bekerja beberapa waktu, menyikapi dana tunjangan sertifikasi 2012 sebesar Rp10 triliun yang mengendap di sejumlah kas pemda, yang sempat heboh.

Irjen Kemendikbud, Haryono Umar menjelaskan, tim ini nantinya merekomendasikan mekanisme yang dianggap paling tepat, agar dana bisa sampai ke kantong guru dengan cepat.

Selain itu, tim juga akan melakukan langkah-langkah penindakan. Jadi, tim ini pula yang akan menelusuri mandeknya dana sertifikasi guru tahun ini, seperti diduga juga terjadi di sejumlah daerah di Sumut. "Nanti akan kita lihat, di mana mandeknya, dan untuk apa uang itu," ujar Haryono Umar kepada JPNN kemarin (27/5).

Tidak hanya pemda yang disasar. Jika memang kemenkeu belum menyalurkan dana dimaksud, maka akan ditanya apa alasannya.

Sebelumnya, Sekretaris Jenderal Kemendikbud Prof Ainun Naim  menyebutkan, alokasi anggaran tunjangan sertifikasi guru tahun 2013 sebesar Rp43 triliun. Tahun 2012 sebesar Rp10 triliun.

Ainun menyebutkan, belum disalurkannya dana tersebut oleh kemenkeu biasanya karena ada masalah data. Dimana kriteria guru penerima belum memenuhi syarat, terutama jumlah jam mengajar. Kemungkinan lain karena pertanggungjawaban atas dana yang ditransfer sebelumnya, belum jelas.

Ainun mengatakan, jika data belum beres dan dana langsung ditransfer, maka bisa muncul masalah baru. Pasalnya, jika ternyata ada guru yang tidak memenuhi syarat sertifikasi telanjur menerima dana tersebut, uang harus dikembalikan lagi.

Haryono tidak menerima alasan-alasan seperti itu. "Itu alasan klasik," cetus mantan pimpinan KPK itu.Menurutnya, data base mestinya sudah ada sejak lama. Jika ada penambahan data, ya cukup data tambahan itu yang diverifikasi.

Jika soal data yang dijadikan dalih, Haryono mengatakan, tim khusus nantinya juga akan menelisik hal itu. Jangan sampai ada pembengkakan data, sedang uangnya tidak jelas masuk ke kantong siapa.

Dia menjanjikan akan serius menggarap persoalan ini. Dikatakan, setelah dirinya membeber data dana sertifikasi guru yang mandek di sejumlah daerah beberapa waktu lalu, ada sejumlah kepala daerah yang lapor ke dirinya.

"Mereka bilang memang dana masih ada di kas daerah," ujarnya. Hanya saja, dia tidak mau menyebut siapa nama kepala daerah dimaksud. (sam/jpnn)

Tunjangan Profesi Guru Tak Kunjung Cair

JAKARTA - Pengurus Besar Persatuan Guru Republik Indonesia (PB-PGRI) kembali menyurati Menteri pendidikan dan kebudayaan Mohammad Nuh agar segera mengurus pencairan Tunjangan Profesi Guru (TPG) di berbagai daerah.

Menurut Ketua Umum PB PGRI, Sulistyo, laporan yang diterimanya hingga awal Mei 2013 ini, belum satupun kabupaten/kota yang tuntas pencairan tujangan profesinya karena persoalan data pokok pendidik (Dapodik) yang tidak beres.

"Saya ke Sulawesi Selatan, Sulawesi Tenggara, Padang, saya menjumpai tidak satupun kabupaten/kota yang selesai dapodiknya sehingga TPG tak bisa dicairkan oleh dinas," kata Sulistyo kepada JPNN.COM, Rabu (29/5).

Dia menjelaskan, berdasarkan laporan dari para guru, alasan daerah belum membayarkan TPG karena surat keputusan penetapan penerima TPG dari Kemdikbud belum mereka terima. Karena itu PB PGRI mendesak Kemdikbud segera menetapkan SK penerima TPG pada guru yang berhak.

Bila lambatnya penetapan SK tersebut karena Dapodik, maka menyusul surat PB PGRI terdahulu, maka PGRI meminta agar pencairan dana TPG itu tidak didasarkan pada Dapodik.

Ditegaskan Sulistyo, sistem penghitungan Dapodik sendiri belum mampu mengakomodasi pelaksanaan di lapangan, bahkan prakteknya semakin lama semakin jelek. Misalnya saja Dapodik SD/SMP baru 60 persen yang selesai, 40 persen lagi bermasalah.

"Masalah utama tidak terpenuhi 24 jam mengajar. Sekolah yang belum punya register tidak bisa masuk sistem karena Dapodik belum mengakomodir guru yang mengajar di luar bidang studinya, padahal di daerah, mereka ditugasi resmi oleh dinas. Artinya guru dirugikan," ujar Anggota DPD RI asal Jateng itu.

Kondisi ini diperparah dengan belum dibayarkannya kekurangan pembayaran TPG tahun 2010, 2011 dan 2012. Karena itu PB PGRI meminta Kemidkbud segera menerbitkan kejelasan informasi waktu kapan pembayaran tunggakan TPG itu dilakukan.(Fat/jpnn)
 
sumber: http://www.jpnn.com/read/2013/05/29/174257/Tunjangan-Profesi-Guru-Tak-Kunjung-Cair-

Bentuk-Bentuk Bilangan Pecahan

Bilangan pecahan dapat dinyatakan dalam beberapa bentuk dan kita dapat mengubahnya dari bentuk yang satu ke bentuk yang lain. Berikut bentuk-bentuk bilangan pecahan dan cara mengubahnya ke bentuk yang lain.

1. Pecahan biasa
 Pecahan biasa adalah bentuk pecahan yang terdiri dari pembilang dan penyebut.


Bilangan-bilangan bulat dapat diubah menjadi bentuk pecahan biasa. Bagaimana kita dapat mengubahnya? Perhatikan pada animasi berikut.
Bentuk pecahan dari bilangan 1, 2 dan 3 adalah (Klik pada tanda panah di atas bilangan 1, 2, dan 3)
http://belajar.kemdiknas.go.id/file_storage/materi_pokok/MP_504/Flash/anim%20hal19.swf


2. Pecahan campuran
 Pecahan campuran adalah bentuk pecahan yang terdiri dari gabungan bilangan bulat dan pecahan biasa.


Kalian dapat mengubah dari pecahan biasa ke pecahan campuran dan sebaliknya dari pecahan campuran menjadi pecahan biasa. Untuk mengetahuinya mari kalian lakukan animasi berikut.

Andi mempunyai 7 keping kue yang akan dimasukkan ke dalam 2 kotak. Setiap kotak harus diisi dengan  keping kue yang sama banyaknya, berapa sisa keping kue yang tidak masuk kotak?
http://belajar.kemdiknas.go.id/file_storage/materi_pokok/MP_504/Flash/hal21.swf
Contoh:
1.    Ubah pecahan berikut ke pecahan campuran.

         (Klik pada tombol jawab)


2.    Ubah pecahan campuran berikut menjadi pecahan biasa

      (Klik pada tombol jawab)

3. Pecahan desimal
Pernahkah kalian melihat bilangan 43,257? Bilangan apakah itu? Untuk mengetahuinya lihat animasi berikut.
(Klik pada tombol play)
Pecahan desimal adalah bentuk pecahan  yang nilai penyebutnya adalah 10, 100, 1000, dan seterusnya dan dinyatakan dengan tanda koma.

Contoh :
1.    Ubah pecahan berikut ke bentuk desimal:
               (Klik pada tombol jawab)

2.    Ubah bilangan desimal berikut ke bentuk pecahan:
a. 0,45
b. 3,128       (Klik pada tombol jawab)
4. Bentuk persen dan permil
Persen adalah bentuk pecahan biasa yang nilai penyebutnya 100 dan dinyatakan dengan lambang %. Permil adalah bentuk pecahan yang nilai penyebutnya 1000 dan menggunakan lambang . Dalam kehidupan sehari-hari kalian sering menemukan perhitungan yang menggunakan persen dan permil, seperti diskon harga di suatu toko.

Orang-orang Yang Terlibat Dalam Sitem Dapodik

   
Sistem pendataan melalui Data Pokok Pendidikan (Dapodik) melibatkan banyak orang mulai dari pusat sampai daerah. Dapodik yang digagas oleh Direktorat Pembinaan Pendidik dan Tenaga Kependidikan Pendidikan Dasar (P2TK Dikdas) mulai diterapkan tahun 2012. Sebagai upaya untuk menjaring data  3 data utama yaitu terkait peserta didik, tenaga kependidikan (guru), dan satuan pendidikan (sekolah). Berikut adalah orang-orang yang terlibat agar sistem Dapodik sukses dijalankan.

    Guru    Guru sebagai orang yang paling tahu data di lapangan, baik terkait dengan data peserta didiknya, sarana dan prasarana kelas, serta data tentang dirinya sendiri. Data-data itulah yang akan diberikan kepada Operator Sekolah untuk dimasukan ke Aplikasi Dapodik dan kemudian diunggah ke server pusat Dapodik. Guru juga harus aktif untuk mengecek datanya yang sudah terekam di P2TK Dikdas.

    Kepala Sekolah    Kepala sekolah sebagai penanggung jawab terhadap kelengkapan dan kebenaran data yang diunggah. Kepala sekolah memberikan informasi terkait guru (pembagian jam mengajar) dan keadaan sekolah, mengenai sarana dan prasarana sekolah beserta kondisinya. Kepala sekolah menugaskan salah seorang tenaga di sekolahnya untuk menjadi Operator Dapodik Sekolah.

    Operator Sekolah    Operator sekolah sebagai orang terpenting sistem Dapodik, mereka mengumpulkan semua data yang harus dimasukan ke Aplikasi Dapodik. Data yang sudah selesai dimasukan, kemudian diunggah secara online. Selain itu, mereka memastikan data sudah terkirim dan benar. Operator sekolah selain memerlukan pedampingan dari guru atau kepala sekolah, juga harus diberikan fasilitas dalam menjalankan tugasnya.

    Operator Dinas Pendidikan Kab/Kota    Operator Dinas Pendidikan Kabupaten/Kota memberikan pelatihan pada operator sekolah tentang teknis pelaksanaan pendataan di sekolah.Operator Dinas Pendidikan Kab/Kota juga membantu perbaikan data, misalnya; memperbaiki NUPTK, mutasi jabatan antar Kab/Kota, alih jabatan (Guru ke Pengawas), konversi bidang studi sertifikasi, mengajukan penambahan jam di luar dikdas, mengusulkan penerbitan Surat Keputusan (SK) tunjangan guru.

    Operator Pusat (P2TK Dikdas)    Operator Pusat memiliki peran dalam approval (persetujuan) perbaikan data kelulusan sertifikasi. Operator pusat akan melakukan verifikasi sebelum mengabulkam permohonan dari Operator Dinas Pendidikan Kab/Kota untuk perbaikan data. Menerbitkan SK bagi guru yang telah memenuhi syarat menerima tunjangan.

    Data dalam Dapodik harus lengkap, wajar dan benar. Dapodik telah ditetapkan sebagai acuan bagi pengambilan kebijakan. Ini sesuai dengan Instruksi Mendikbud Nomor 02 Tahun 2011, bahwa hasil Dapodik menjadi satu-satunya sumber (acuan) data pendidikan dalam pelaksanaan kegiatan dan pengambilan keputusan atau kebijakan pendidikan.

sumber: SekolahDasar.Net 23 Mei 2013

Pengumuman Kelulusan UN SD/MI Tahun 2013

    Ujian Nasional (UN) 2013 telah berakhir dan diikuti oleh peserta didik  tingkat SD sampai SMA/SMK. Saat ini, yang dinanti adalah pengumuman hasilnya, termasuk peserta didik SD/MI yang telah melaksanakannya pada tanggal 6 sampai 8 Mei yang lalu. UN tingkat SD ini mengujikan tiga mata pelajaran, yaitu Bahasa Indonesia, Matematika dan Ilmu Pengetahuan Alam (IPA).
    Berdasarkan Prosedur Operasi Standar (POS) UN SD/MI 2013 yang dikeluarkan Badan Nasional Standar Pendidikan (BNSP), Penyelenggara UN Tingkat Provinsi mengirim hasil UN ke Penyelenggara UN Tingkat Kabupaten/Kota paling lambat tanggal 3 Juni 2013. Pengumuman kelulusan peserta didik dari satuan pendidikan (sekolah) paling lambat tanggal 8 Juni 2013.
    Untuk peserta didik SD/MI, Kelulusan UN (NA) ditentukan berdasarkan gabungan nilai Ujian Sekolah (US) dan nilai rata-rata rapor semester 7, 8, 9, 10, dan 11. Dengan pembobotan 60% untuk nilai US dan 40% untuk nilai rata-rata rapor menjadi Nilai Sekolah (NS). Nilai Akhir (NA) didapat dari nilai rata-rata gabungan NS dari 3 mata pelajaran yang diujinasionalkan dan nilai UN dengan formula 60% nilai UN dan 40% nilai sekolah (NS).
    Kriteria kelulusan UN SD/MI ditetapkan melalui rapat dewan guru berdasarkan nilai minimal setiap mata pelajaran yang diujinasionalkan dan nilai rata-rata ketiga mata pelajaran yang diujinasionalkan. Peserta didik dinyatakan lulus dari satuan pendidikan (sekolah) ditentukan melalui rapat dewan guru dengan ketentuan:
        Menyelesaikan seluruh program pembelajaran.
        Memperoleh nilai minimal baik pada penilaian akhir untuk seluruh mata pelajaran.
        LulusUjian Sekolah/Madrasah
        Lulus UN

    Untuk tahun depan yaitu tahun pelajaran 2013/2014, berdasarkan Peraturan Pemerintah Nomor 32 Tahun 2013 tentang tentang Standar Nasional Pendidikan. Kelulusan untuk untuk tingkat SD/MI hanya ditentukan berdasarkan tiga kriteria (a. Menyelesaikan seluruh program Pembelajaran; b. Memperoleh nilai minimal baik pada penilaian akhir untuk seluruh mata pelajaran; c. Lulus ujian sekolah/madrasah). Tidak ada lagi ketentuan lulus UN.

sumber: SekolahDasar.Net 21 Mei 2013

Hubungan Antar Pecahan


Dapatkah kalian menentukan hubungan antar kedua bilangan pecahan itu? Apakah kedua bilangan pecahan itu senilai (=), atau yang satu lebih dari yang lain (>), atau yang satu kurang dari yang lain (<)?.

Untuk dapat mengetahuinya, lakukan simulasi berikut.

Dengan demikian menentukan hubungan antar bilangan pecahan dapat dilakukan jika bilangan-bilangan pecahan tersebut diubah ke pecahan-pecahan senilai yang nilai peyebutnya sama. Menyamakan penyebut dengan menggunakan kelipatan persekutuan terkecil (KPK). Dengan demikian kita dapat menyatakan hubungan lebih dari (>), kurang dari (<) atau sama dengan (=) dan mengurutkan beberapa bilangan pecahan dengan membandingkan angka pembilangnya.


sumber: http://belajar.kemdiknas.go.id/index3.php?display=view&mod=script&cmd=Bahan%20Belajar/Materi%20Pokok/SMP/view&id=504&uniq=4461

Menyederhanakan Pecahan

Menyederhanakan suatu bilangan pecahan adalah menentukan pecahan senilai dari bilangan pecahan itu dengan cara membagi pembilang dan penyebut dengan faktor persekutuan terbesarnya (FPB).

Perhatikan pada panel animasi. Klik pada tombol play.

Pecahan Senilai


  Pada gambar, daerah berwarna biru tua menunjukkan nilai /luas yang sama.

  Mengapa disebut pecahan senilai? Karena pecahan senilai didapat dengan cara :


Ahmad Zainuddin: DPR Desak Pemerintah Tunda Implementasi Kurikulum Baru

Rencana implementasi kurikulum baru di bulan Juli 2013 oleh Kementerian Pendidikan & Kebudayaan (Kemendikbud) terkesan sangat dipaksakan. Dengan persiapan daya dukung kurikulum yang minim dari pemerintah, selayaknya implementasi kurikulum lebih baik di lakukan pada tahun 2014 nanti. Biarkan selama setahun ke depan pemerintah melakukan uji coba kurikulum sambil menyempurnakan persiapan kurikulum yang utuh.
Demikian di katakan oleh Ahmad Zainuddin, anggota panja kurikulum komisi X DPR RI dari Fraksi PKS, menanggapi rencana pemerintah yang tetap ngotot akan melaksanakan tahun 2013 ini.
Zainuddin menjelaskan jika persiapan yang kurang dikhawatirkan akan menimbulkan masalah baru.
“Lihat saja pelaksanaan UN, akibat adanya perubahan kebijakan secara teknis akhirnya menimbulkan kekisruhan pelaksanaan UN yang tertunda di 11 provinsi. Pemerintah harus introspeksi dan mawas diri tentang kesalahan dalam pelaksanaan UN dan jangan mengulangi lagi kesalahan yang sama di dalam pelaksanaan kurikulum nanti,” ujarnya.
Menyikapi tentang pengajuan anggaran kurikulum yang baru dari pemerintah, Zainuddin menyangsikan keakuratan dan sinkronisasi antara mata anggaran dengan data sekolah sasaran yang disampaikan oleh pemerintah.
Pasalnya pada pengajuan awal, kemendikbud mengajukan anggaran sekitar 600 Miliar untuk implementasi kurikulum dengan sekolah sasaran 30 % SD, 100% SMP dan SMA. Sedangkan pada pengajuan akhir dengan anggaran 800 Miliar, justru ada penurunan sekolah sasaran yaitu 5 % SD, 7 % SMP dan SMA 100%.
Zainuddin menambahkan bahwa sampai saat ini pemerintah belum menyampaikan kepada komisi X tentang dokumen kurikulum 2013 secara utuh untuk seluruh jenjang pendidikan sesuai dengan PP 32 Tahun 2013 tentang Standar Nasional Pendidikan yang baru pengganti PP 19 Tahun 2005. “Artinya, jika pemerintah akan melaksanakan kurikulum baru sesuai aturan maka pemerintah  wajib menyampaikan dokumen kurikulum yang lengkap ke DPR,” tambahnya.
Selain itu, persoalan penyediaan buku dan juga pelatihan guru dengan waktu yang singkat akan berakibat hasil yang diharapkan tidak tercapai dengan optimal. Untuk buku, Zainuddin menjelaskan bahwa minimal dalam penyusunan buku harus ada validasi dari BSNP. Sedang mengenai pelatihan guru, waktu yang tersedia tidak cukup. “Untuk sosialisasi dan uji coba kurikulum saja butuh waktu minimal satu semester,” imbuh nya.
Untuk itu, legislator PKS dapil DKI Jakarta 1 ini menegaskan agar pemerintah tidak terburu-buru untuk melaksanakan kurikulum baru di tahun ini. “Kita mengapresiasi pemerintah jika dengan melihat persiapan yang kurang tersebut mereka legowo untuk menunda nya hingga tahun depan, minimal tahun ini kurikulum baru tersebut diuji coba terlebih dahulu,” tutup Zainuddin. (loi/sbb/dakwatuna.com)

Layanan PADAMU NEGERI BPSDMPK-PMP resmi dirilis

Salam Kebangkitan Nasional.
Bertepatan di Hari Kebangkitan Nasional 20 Mei 2013, situs Layanan PADAMU NEGERI BPSDMPK-PMP resmi dirilis dengan semangat membangkitkan Pelayanan Publik Prima, bukan sekedar Pelayanan Birokrasi, kepada Dunia Pendidikan Indonesia.
Kami himbau kepada semua pemilik NUPTK untuk mencari data masing-masing di situs ini dan mempersiapkan diri dalam proses VerVal Ulang NUPTK mulai 3 Juni 2013 sesuai jenis Formulir VerVal Ulang ke Admin Dinas Kab/Kota atau Admin Sekolah Induk masing-masing.
Bagi Admin Dinas dan Sekolah-Sekolah dapat mulai mengaktifkan akun login masing-masing. Surat Login PADAMU NEGERI Admin Dinas dapat diambil di LPMP setempat. Dan Surat Aktifasi Akun Login PADAMU NEGERI setiap sekolah dapat diambil dari Admin Dinas masing-masing.
Mohon bantuan dan pengertian bagi seluruh pihak untuk saling mendukung dan bersinergi membantu proses distribusi dan aktifasi akun login masing-masing.
Hormat Kami
Tim Admin Pusat
PADAMU NEGERI INDONESIA-ku
BPSDMPK-PMP KEMDIKBUD 2013

Tentang NUPTK

NUPTK (Nomor Unik Pendidik dan Tenaga Kependidikan) merupakan kode identitas unik yang diberikan kepada seluruh Pendidik (Guru) dan Tenaga Kependidikan (Staf) di seluruh satuan pendidikan (Sekolah) di Indonesia.
NUPTK dibangun oleh Direktorat Peningkatan Mutu Pendidik dan Tenaga Kependidikan (PMPTK) Depdiknas tahun 2006.
Seiring dengan program Reformasi Birokrasi, NUPTK sejak tahun 2011 dikelola oleh Sekretariat Badan Pengembangan SDM Pendidikan dan Kebudayaan dan Penjaminan Mutu Pendidikan (BPSDMPK-PMP) Kementerian Pendidikan dan Kebudayaan Negara Kesatuan Republik Indonesia.
Dalam perkembangannya, NUPTK menjadi syarat utama yang harus dimiliki oleh seluruh PTK se-Indonesia untuk dapat mengikuti program-program Kementrian lainnya, antara lain:
  • Sertifikasi PTK
  • Uji Kompetensi PTK
  • Diklat PTK, dan
  • Aneka Tunjangan PTK

Mengapa harus VerVal Ulang NUPTK 2013?

  1. NUPTK yang dikelola oleh PMPTK sejak tahun 2006 - 2010 kemudian dikelola oleh BPSDMPK-PMP sejak 2011 menjadi kode referensi utama untuk dapat mengikuti berbagai program pengembangan PTK yang dilaksanakan oleh Kemdikbud, antara lain: Sertifikasi, Uji Kompetensi, Diklat, dan Aneka Tunjangan PTK lainnya.
  2. BPSDMPK-PMP yang bertanggungjawab sepenuhnya terhadap pengelolaan NUPTK sangat berkepentingan melakukan VerVal Ulang NUPTK 2013 dalam rangka meningkatkan penjaminan mutu pendidikan nasional khususnya para PTK.
  3. Dengan peran aktif PTK dalam melaksanakan program VerVal Ulang NUPTK periode 2013 ini. BPSDMPK-PMP dapat membantu progress penjaminan peningkatan mutu para PTK dengan lebih obyektif, transparan, akurat dan berkesinambungan.
  4. Data PTK hasil VerVal Ulang NUPTK yang dikelola oleh BPSDMPK-PMP akan menjadi sumber referensi utama untuk pelaksanaan program-program peningkatan mutu PTK yang dilaksanakan oleh Direktorat Kemdikbud terkait pada tahapan selanjutnya.

Apa manfaat bagi PTK?

  1. Setiap PTK diberi akun login untuk dapat memutakhirkan data personal masing-masing setiap saat setiap waktu darimana saja secara online 24 jam.
  2. Setiap PTK akan diberi fasilitas media jejaring sosial untuk saling berbagi, berkomunikasi dan berkolaborasi antar PTK se-Indonesia.
  3. Setiap PTK akan memiliki Kartu Digital NUPTK yang uptodate di http://padamu.kemdikbud.go.id/kode_nuptk (dalam proses pengembangan)
  4. Setiap PTK akan diberi fasilitas ruang penyimpanan (storage) online untuk menyimpan beragam arsip dokumen secara digital seperti: Ijazah, Sertifikat, Piagam-Piagam, Surat Tugas, dan lain sebagainya (dalam proses pengembangan)

Pemutakhiran Data NUPTK


Mulai bulan Mei 2013, BPSDMPK-PMP menyelenggarakan kegiatan Pemutakhiran Data NUPTK, yang wajib diikuti oleh PTK.
Pemilik NUPTK dan masih aktif sebagai PTK (Pendidik & Tenaga Kependidikan) silakan melakukan pemutakhiran dengan mengunduh Formulir, dan mengikuti prosedur yang ada disitus ini. Bagi PTK yang tidak melakukan pemutakhiran data NUPTK, otomatis akan dinyatakan TIDAK AKTIF.

Mengapa harus VerVal Ulang NUPTK 2013?

Melalui kegiatan PADAMU NEGERI yang dikelola BPSDMPK-PMP ini, Data PTK hasil VerVal Ulang NUPTK akan menjadi sumber referensi utama untuk pelaksanaan program-program peningkatan mutu PTK yang dilaksanakan oleh Direktorat Kemdikbud terkait pada tahapan selanjutnya. [ baca selengkapnya » ]

Wilayah Pelaksanaan

Kegiatan ini (yang juga merupakan registrasi ulang Sekolah) dilaksanakan di tingkat Kota / Kabupaten, Kecamatan maupun Sekolah diseluruh wilayah Indonesia.

Pengertian Pecahan


 Perhatikan pada kasus berikut.
   Seorang ibu membawa satu loyang kue tart. Lalu kue tart itu dibagi menjadi 8 potong yang sama besar dan dibagikan kepada ketiga anaknya Ali, Berman, dan Cipto. Ali mendapat 3 potong, Berman mendapat 1 potong   sisanya untuk Cipto.
   
   Bagaimana kalian dapat menentukan berapa bagian yang diterima oleh masing-masing anak tersebut?
 
    Perhatikan animasi berikut. Untuk memulai animasi klik pada tombol play.

sumber: http://belajar.kemdiknas.go.id/index3.php?display=view&mod=script&cmd=Bahan%20Belajar/Materi%20Pokok/SMP/view&id=504&uniq=4433
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Requirements of a Circuit

Suppose that you were given a small light bulb, an electrochemical cell and a bare copper wire and were asked to find the four different arrangements of the three items that would result in the formation of an electric circuit that would light the bulb. What four arrangements would result in the successful lighting of the bulb? And more importantly, what does each of the four arrangements have in common that would lead us into an understanding of the two requirements of an electric circuit?
The activity itself is a worthwhile activity and if not performed before, one ought to try it before reading further. Like many lab activities, there is power in the actual engagement in the activity that cannot be replaced by simply reading about it. When this activity is performed in the physics classroom, there are numerous observations that can be made by watching a class full of students eager to find the four arrangements. The following arrangements are often tried and do not result in the lighting of the bulb.
After a few minutes of trying, several healthy chuckles, and an occasional exclamation of how hot the wire is getting, a couple of students become successful at lighting the bulb. Unlike the above attempts, the first successful attempt is characterized by the production of a complete conducting loop from the positive terminal to the negative terminal, with both the battery and the light bulb being part of the loop. As shown in the diagram at the right, the base of the light bulb connects to the positive terminal of the cell and the wire extends from the ribbed sides of the light bulb down to the negative terminal of the cell. A complete conducting loop is made with the light bulb being part of the loop. A circuit exists and charge flows along the complete conducting path, lighting the bulb in the process. Compare the arrangement of the cell, bulb and wire at the right to the unsuccessful arrangements shown above. In attempt A, the wire does not loop back to the negative terminal of the cell. In attempt B, the wire does form a loop but not back to the negative terminal of the cell. In attempt C, there is no complete loop at all. Attempt D resembles attempt B in that there is a loop but not from the positive terminal to the negative terminal. And in attempt E, there is a loop and it does go from positive terminal to negative terminal; this is a circuit but the light bulb is not included as part of it. CAUTION: Attempt E will cause your fingers to get hot as you hold the bare wire and charge begins to flow at a high rate between the positive and negative terminals.

Light Bulb Anatomy
Once one group of students successfully lights the bulb, many other lab groups quickly follow suit. But then the question emerges as to what other ways that the cell, bulb and bare wire can be arranged in such a manner as to light the bulb. Often a short light bulb anatomy lesson prompts the lab groups into a quick discovery of one or more of the remaining arrangements.
A light bulb is a relatively simple device consisting of a filament resting upon or somehow attached to two wires. The wires and the filament are conducting materials that allow charge to flow through them. One wire is connected to the ribbed sides of the light bulbs. The other wire is connected to the bottom base of the light bulb. The ribbed edge and the bottom base are separated by an insulating material that prevents the direct flow of charge between the bottom base and the ribbed edge. The only pathway by which charge can make it from the ribbed edge to the bottom base or vice versa is the pathway that includes the wires and the filament. Charge can either enter the ribbed edge, make the pathway through the filament and exit out the bottom base; or it can enter the bottom base, make the pathway through the filament and exit out the ribbed edge. As such, there are two possible entry points and two corresponding exit points.
The successful means of lighting the bulb as shown above involved placing the bottom base of the bulb on the positive terminal and connecting the ribbed edge to the negative terminal using a wire. Any charge that enters the light bulb at the bottom base exits the bulb at the location where the wire makes contact with the ribbed edge. Yet the bottom base does not have to be the part of the bulb that touches the positive terminal. The bulb will light just as easily if the ribbed edge is placed on top of the positive terminal and the bottom base is connected to the negative terminal using a wire. The final two arrangements that lead to a lit light bulb involve placing the bulb at the negative terminal of the cell, either by making contact to it with the ribbed edge or with the bottom base. A wire must then connect the other part of the bulb to the positive terminal of the cell.


The Requirement of a Closed Conducting Path
There are two requirements that must be met to establish an electric circuit. The first is clearly demonstrated by the above activity. There must be a closed conducting path that extends from the positive terminal to the negative terminal. It is not enough that there is simply a closed conducting loop; the loop itself must extend from the positive terminal to the negative terminal of the electrochemical cell. An electric circuit is like a water circuit at a water park. The flow of charge through wires is similar to the flow of water through the pipes and along the slides at a water park. If a pipe gets plugged or broken such that water cannot make the complete path through the circuit, then the flow of water will soon cease. In an electric circuit, all connections must be made and made by conducting materials capable of carrying charge. As the cell, bulb and wire experiment continues, some students explore the capability of various materials to carry a charge by inserting them in their circuit. Metallic materials are conductors and can be inserted into the circuit to successfully light the bulb. On the other hand, paper and plastic materials are typically insulators and their insertion within the circuit will hinder the flow of charge to such a degree that the current ceases and the bulb no longer lights. There must be a closed conducting loop from the positive to the negative terminal in order to establish a circuit and to have a current.
With an understanding of this first requirement of an electric circuit, it becomes clear what is happening when an incandescent light bulb in a table lamp or floor lamp no longer works. Over time, a light bulb filament becomes weak and brittle can often break or simply become loose. When this occurs, the circuit is opened and a closed conducting loop no longer exists. Without a closed conducting loop, there can be no circuit, no charge flow and no lit bulb. Next time you find a broken bulb in a lamp, safely remove it and inspect the filament. Often times, shaking the removed bulb will cause a rattle; the filament has likely fallen off the supporting posts that it normally rests upon to the bottom of the glass globe. When shook, you will hear the rattle of the filament hitting the glass globe.


The Requirement of an Energy Supply
The second requirement of an electric circuit that is common in each of the successful attempts demonstrated above is that there must be an electric potential difference across the two ends of the circuit. This is most commonly established by the use of an electrochemical cell, a pack of cells (i.e., a battery) or some other energy source. It is essential that there is some source of energy capable of increasing the electric potential energy of a charge as it moves from the low energy terminal to the high energy terminal. As discussed in Lesson 1, it takes energy to move a positive test charge against the electric field. As applied to electric circuits, the movement of a positive test charge through the cell from the low energy terminal to the high energy terminal is a movement against the electric field. This movement of charge demands that work be done on it in order to lift it up to the higher energy terminal. An electrochemical cell serves the useful role of supplying the energy to do work on the charge in order to pump it or move it through the cell from the negative to the positive terminal. By doing so, the cell establishes an electric potential difference across the two ends of the electric circuit. (The concept of an electric potential difference and its application to electric circuits was discussed in detail in Lesson 1.)
In household circuits, the energy is supplied by a local utility company that is responsible for making sure that the hot and the neutral plates within the circuit panel box of your home always have an electric potential difference of about 110 Volts to 120 Volts (in the United States). In typical lab activities, an electrochemical cell or group of cells (i.e., a battery) is used to establish an electric potential difference across the two ends of the external circuit of about 1.5 Volts (a single cell) or 4.5 Volts (three cells in a pack). Analogies are often made between an electric circuit and the water circuit at a water park or a roller coaster ride at an amusement park. In all three cases, there is something that is moving through a complete loop - that is, through a circuit. And in all three cases, it is essential that the circuit include a section where energy is put into the water, the coaster car or the charge in order to move it uphill against its natural direction of motion from a low potential energy to a high potential energy. A water park ride has a water pump that pumps the water from ground level to the top of the slide. A roller coaster ride has a motor-driven chain that carries the train of coaster cars from ground level to the top of the first drop. And an electric circuit has an electrochemical cell, battery (group of cells) or some other energy supply that moves the charge from ground level (the negative terminal) to the positive terminal. By constantly supplying the energy to move the charge from the low energy, low potential terminal to the high energy, high potential terminal, and a continuous flow of charge can be maintained.
By establishing this difference in electric potential, charge is able to flow downhill through the external circuit. This motion of the charge is natural and does not require energy. Like the movement of water at a water park or a roller coaster car at an amusement park, the downhill motion is natural and occurs without the need for energy from an external source. It is the difference in potential - whether gravitational potential or electric potential - that causes the water, the coaster car and the charge to move. This potential difference requires the input of energy from an external source. In the case of an electric circuit, one of the two requirements to establish an electric circuit is an energy source.


In conclusion, there are two requirements that must be met in order to establish an electric circuit. The requirements are
  1. There must be an energy supply capable doing work on charge to move it from a low energy location to a high energy location and thus establish an electric potential difference across the two ends of the external circuit.
  2. There must be a closed conducting loop in the external circuit that stretches from the high potential, positive terminal to the low potential, negative terminal.
http://www.physicsclassroom.com/Class/circuits/u9l2b.cfm

Electric Circuit

To be a true circuit, charges must continually flow through a complete loop, returning to their original position and cycling through again. If there were a means of moving positive charge from the negative plate back up onto the positive plate, then the movement of positive charge downward through the charge pipe (i.e., the wire) would occur continuously. In such a case, a circuit or loop would be established.
A common lab activity that illustrates the necessity of a complete loop utilizes a battery pack (a collection of D cells), a light bulb, and some connecting wires. The activity involves observing the affect of connecting and disconnecting a wire in a simple arrangement of the battery pack, light bulbs and wires. When all connections are made to the battery pack, the light bulb lights. In fact, the lighting of the bulb occurs immediately after the final connection is made. There is no perceivable time delay between when the last connection is made and when the light bulb is perceived to light up.
The fact that the light bulb lights and remains lit is evidence that charge is flowing through the light bulb filament and that an electric circuit has been established. A circuit is simply a closed loop through which charges can continuously move. To demonstrate that charges are not only moving through the light bulb filament but also through the wires connecting the battery pack and the light bulb, a variation on the above activity is made. A compass is placed beneath the wire at any location such that its needle is placed in alignment with the wire. Once the final connection is made to the battery pack, the light bulb lights and the compass needle deflects. The needle serves as a detector of moving charges within the wire. When it deflects, charges are moving through the wire. And if the wire is disconnected at the battery pack, the light bulb is no longer lit and the compass needle returns to its original orientation. When the light bulb lights, charge is moving through the electrochemical cells of the battery, the wires and the light bulb filaments; the compass needle detects the movement of this charge. It can be said that there is a current - a flow of charge within the circuit.
The electric circuit demonstrated by the combination of battery, light bulb and wires consists of two distinct parts: the internal circuit and the external circuit. The part of the circuit containing electrochemical cells of the battery is the internal circuit. The part of the circuit where charge is moving outside the battery pack through the wires and the light bulb is the external circuit. In Lesson 2, we will focus on the movement of charge through the external circuit. In the next part of Lesson 2 we will explore the requirements that must be met in order to have charge flowing through the external circuit.

http://www.physicsclassroom.com/Class/circuits/u9l2a.cfm

Struktur Kurikulum 2013


Dalam teori kurikulum (Anita Lie, 2012) keberhasilan suatu kurikulum merupakan proses panjang, mulai dari kristalisasi berbagai gagasan dan konsep ideal tentang pendidikan, perumusan desain kurikulum, persiapan pendidik dan tenaga kependidikan, serta sarana dan prasarana, tata kelola pelaksanaan kurikulum --termasuk pembelajaran-- dan penilaian pembelajaran dan kurikulum.
Struktur kurikulum dalam hal perumusan desain kurikulum, menjadi amat penting. Karena begitu struktur yang disiapkan tidak mengarah sekaligus menopang pada apa yang ingin dicapai dalam kurikulum, maka bisa dipastikan implementasinya pun akan kedodoran.



Pada titik inilah, maka penyampaian struktur kurikulum dalam uji publik ini menjadi penting. Tabel 1 menunjukkan dasar pemikiran perancangan struktur kurikulum SD, minimal ada sebelas item. Sementara dalam rancangan struktur kurikulum SD ada tiga alternatif yang di mesti kita berikan masukan.

Di jenjang SMP usulan rancangan struktur kurikulum diperlihatkan pada tabel 2. Bagaimana dengan jenjang SMA/SMK? Bisa diturunkan dari standar kompetensi lulusan (SKL) yang sudah ditentukan, dan juga perlu diberikan masukan.

Tiga Persiapan untuk Implementasi Kurikulum 2013

ADA pertanyaan yang muncul bernada khawatir, dalam uji publik kurikulum 2013? Persiapan apa yang dilakukan Kemdikbud untuk kurikulum 2013? Apakah sedemikian mendesaknya, sehingga tahun pelajaran 2013 mendatang, kurikulum itu sudah harus diterapkan. Menjawab kekhawatiran itu, sedikitnya ada tiga persiapan yang sudah masuk agenda Kementerian untuk implementasi kurikulum 2013. Pertama, berkait dengan buku pegangan dan buku murid. Ini penting, jika kurikulum mengalami perbaikan, sementara bukunya tetap, maka bisa jadi kurikulum hanya sebagai “macan kertas”.

Pemerintah bertekad untuk menyiapkan buku induk untuk pegangan guru dan murid, yang tentu saja dua buku itu berbeda konten satu dengan lainnya.

Kedua, pelatihan guru. Karena implementasi kurikulum dilakukan secara bertahap, maka pelatihan kepada guru pun dilakukan bertahap. Jika implementasi dimulai untuk kelas satu, empat di jenjang SD dan kelas tujuh, di SMP, serta kelas sepuluh di SMA/SMK, tentu guru yang diikutkan dalam pelatihan pun, berkisar antara 400 sampai 500 ribuan.

Ketiga, tata kelola. Kementerian sudah pula mnemikirkan terhadap tata kelola di tingkat satuan pendidikan. Karena tata kelola dengan kurikulum 2013 pun akan berubah. Sebagai misal, administrasi buku raport. Tentu karena empat standar dalam kurikulum 2013 mengalami perubahan, maka buku raport pun harus berubah.

Intinya jangan sekali-kali persoalan implementasi kurikulum dihadapkan pada stigma persoalan yang kemungkinan akan menjerat kita untuk tidak mau melakukan perubahan. Padahal kita sepakat, perubahan itu sesuatu yang niscaya harus dihadapi mana kala kita ingin terus maju dan berkembang. Bukankah melalui perubahan kurikulum ini sesungguhnya kita ingin membeli masa depan anak didik kita dengan harga sekarang.

Cara Melihat Tempat Uji Kompetensi Guru 2013


Uji kompetensi guru (UKG) 2013 sebelumnya dikabarkan akan digelar pertengahan Mei 2013, tetapi masih belum jelas tanggal berapa uji kompetensi bagi guru belum sertifikasi tersebut dilaksanakan. Meskipun demikian, tempat uji kompetensi sudah bisa dilihat di website Informasi Peserta Sertifikasi Guru atau Sergur Kemdiknas.

Bisa dilihat status peserta UKG 2013 yang ditelusuri di situs resmi Sergur Kemdiknas yaitu terdapat status data terakhir sudah diverifikasi oleh tempat ujian. Selain itu bisa dilihat juga tempat uji kompetensi bagi guru tersebut. Berikut adalah cara untuk melihat atau mengecek tempat uji kompetensi guru:

  1. Kunjungi http://sergur.kemdiknas.go.id/sg13/
  2. Pada pojok kanan atas, pilih Pencarian
  3. Masukan 16 digit NUPTK, dan ikon pencarian
  4. Jika NUPTK benar, muncullah datanya

Apakah hasil UKG menentukan penetapan peserta Sergur 2013?
Berdasarkan Buku Pedoman Penetapan Peserta Sertifikasi Guru 2013, hasil uji kompetensi juga menjadi dasar penetapan peserta sertifikasi guru 2013. Badan Pengembangan Sumberdaya Manusia Pendidikan dan Penjaminan Mutu Pendidikan (PSDMPK-PMP) menetapkan peserta sertifikasi guru tahun 2013 berdasarkan:
1.) Urutan prioritas penetapan peserta sertifikasi guru 2013.
2.) Hasil perangkingan berdasarkan usia, masa kerja, dan pangkat.
3.) Skor uji kompetensi guru

Penetapan peserta sertifikasi guru 2013 dilaksanakan setelah selesai UKG. Uji kompetensi diikuti seluruh guru yang belum memiliki sertifikat pendidik dan telah memenuhi persyaratan. Perangkingan dilakukan oleh sistem yang terintegrasi dengan data base NUPTK dan dipublikasikan secara online. Sedangkan penetapan kuota peserta berdasarkan keseimbangan usia dan keadilan proporsional jumlah peserta antar provinsi.

sumber :

UKG Dilaksanakan Mulai 27 Mei Sampai 8 Juni 2013


Uji kompetensi guru (UKG) untuk guru yang belum memiliki sertifikat pendidik oleh Kementerian Pendidikan dan Kebudayaan (Kemdikbud) akan dilaksanakan mulai tanggal 27 Mei sampai dengan 8 Juni 2013. Untuk jadwal di Kabupaten/Kota akan diinformasikan melalui Dinas Pendidikan setempat yang berkoordinasi dengan Lembaga Penjaminan Mutu Pendidikan (LPMP).

Guru TK sampai dengan SMA/SMK terdaftar sebagai peserta uji kompetensi. Sehubungan dengan tidak adanya mata pelajaran TIK pada struktur kurikulum SMP dan SMA tahun 2013, maka UKG tahun 2013 tidak ada mata uji TIK. Oleh Karena itu, peserta UKG mata pelajaran TIK dapat mengubah ke mata pelajaran lain sesuai dengan ketentuan dan persyaratan peserta sertifikasi guru.

UKG 2013 berfungsi sebagai pemetaan kompetensi guru yang meliputi kompetensi pedagogik dan kompetensi profesional. Adapun untuk bisa ikut sertifikasi, harus mengacu pada aturan yang ada, yakni melihat usia dan golongan masa kerja. Jadi tidak semua guru yang lulus UKG nanti akan otomatis menjadi peserta Pendidikan dan Pelatihan Profesi Guru (PLPG).

Peserta sertifikasi tahun 2013, selain peserta yang lulus UKG 2013, yang juga diprioritaskan adalah guru yang belum lulus pada UKA 2012, tetapi sudah mengikuti pelatihan, serta guru yang tidak lulus dalam PLPG tahun 2011.

UKG tahun ini dilaksanakan dengan menggunakan dua sistem, yaitu sistem online dan sistem manual. Sistem Online dilaksanakan pada daerah yang terjangkau jaringan internet dan memiliki laboratorium komputer yang terhubung ke jaringan intranet. UGK dilaksanakan di Tempat Uji Kompetensi (TUK) dengan didampingi oleh operator dan pengawas ujian.

Sistem manual dilaksanakan pada daerah yang tidak terjangkau jaringan internet dan tidak memiliki laboratorium komputer. Soal UKG 2013 terdiri dari 100 soal dengan komposisi soalnya meliputi 30% kompetensi pedagogik dan 70% kompetensi profesional. Waktu yang disediakan untuk mengerjakan soal adalah 120 menit.

sumber : sekolahdasar[dot]net

Magnet





A magnet (from Greek μαγνήτις λίθος magnḗtis líthos, "Magnesian stone") is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, and attracts or repels other magnets.

A permanent magnet is an object made from a material that is magnetized and creates its own persistent magnetic field. An everyday example is a refrigerator magnet used to hold notes on a refrigerator door. Materials that can be magnetized, which are also the ones that are strongly attracted to a magnet, are called ferromagnetic (or ferrimagnetic). These includeiron, nickel, cobalt, some alloys of rare earth metals, and some naturally occurring minerals such as lodestone. Although ferromagnetic (and ferrimagnetic) materials are the only ones attracted to a magnet strongly enough to be commonly considered magnetic, all other substances respond weakly to a magnetic field, by one of several other types of magnetism.


Ferromagnetic materials can be divided into magnetically "soft" materials like annealed iron, which can be magnetized but do not tend to stay magnetized, and magnetically "hard" materials, which do. Permanent magnets are made from "hard" ferromagnetic materials such as alnico and ferrite that are subjected to special processing in a powerful magnetic field during manufacture, to align their internal microcrystalline structure, making them very hard to demagnetize. To demagnetize a saturated magnet, a certain magnetic field must be applied, and this threshold depends on coercivity of the respective material. "Hard" materials have high coercivity, whereas "soft" materials have low coercivity.


An electromagnet is made from a coil of wire that acts as a magnet when an electric currentpasses through it but stops being a magnet when the current stops. Often, the coil is wrapped around a core of "soft" ferromagnetic material such as steel, which greatly enhances the magnetic field produced by the coil.


The overall strength of a magnet is measured by its magnetic moment or, alternatively, the total magnetic flux it produces. The local strength of magnetism in a material is measured by its magnetization.








Contents

[hide]
1 Discovery and development
2 Background on the physics of magnetism and magnets
2.1 Magnetic field
2.2 Magnetic moment
2.3 Magnetization
2.4 Modelling magnets
2.5 Pole naming conventions
2.6 Magnetic materials
3 Common uses of magnets
4 Medical issues and safety
5 Magnetizing ferromagnets
6 Demagnetizing ferromagnets
7 Types of permanent magnets
7.1 Magnetic metallic elements
7.2 Composites
7.3 Rare-earth magnets
7.4 Single-molecule magnets (SMMs) and single-chain magnets (SCMs)
7.5 Nano-structured magnets
7.6 Costs
7.7 Temperature
8 Electromagnets
9 Units and calculations
9.1 Fields of a magnet
9.2 Calculating the magnetic force
9.2.1 Pull force of a single magnet
9.2.2 Force between two magnetic poles
9.2.3 Force between two nearby magnetized surfaces of area A
9.2.4 Force between two bar magnets
9.2.5 Force between two cylindrical magnets
10 See also
11 Notes
12 References
13 External links

Discovery and development


Main article: History of electromagnetism


See also: Magnetism history


Ancient people learned about magnetism from lodestones, naturally magnetized pieces of iron ore. They are naturally created magnets, which attract pieces of iron. The word magnet in Greek meant "stone from Magnesia",[1] a part of ancient Greece where lodestones were found. Lodestones suspended so they could turn were the first magnetic compasses. The earliest known surviving descriptions of magnets and their properties are from Greece, India, and China around 2500 years ago.[2][3][4] The properties of lodestones and their affinity for iron were written of by Pliny the Elder in his encyclopedia Naturalis Historia.[5]


By the 12th to 13th centuries AD, magnetic compasses were used in navigation in China, Europe, and elsewhere.[6]
Background on the physics of magnetism and magnets
Magnetic field







Iron filings that have oriented in the magnetic field produced by a bar magnet


Main article: Magnetic field


The magnetic flux density (also called magnetic B field or just magnetic field, usually denoted B) is a vector field. The magnetic B field vector at a given point in space is specified by two properties:
Its direction, which is along the orientation of a compass needle.
Its magnitude (also called strength), which is proportional to how strongly the compass needle orients along that direction.


In SI units, the strength of the magnetic B field is given in teslas.[7]
Magnetic moment


Main article: Magnetic moment


A magnet's magnetic moment (also called magnetic dipole moment and usually denoted μ) is a vector that characterizes the magnet's overall magnetic properties. For a bar magnet, the direction of the magnetic moment points from the magnet's south pole to its north pole,[8] and the magnitude relates to how strong and how far apart these poles are. In SI units, the magnetic moment is specified in terms of A•m2.


A magnet both produces its own magnetic field and responds to magnetic fields. The strength of the magnetic field it produces is at any given point proportional to the magnitude of its magnetic moment. In addition, when the magnet is put into an external magnetic field, produced by a different source, it is subject to a torque tending to orient the magnetic moment parallel to the field.[9] The amount of this torque is proportional both to the magnetic moment and the external field. A magnet may also be subject to a force driving it in one direction or another, according to the positions and orientations of the magnet and source. If the field is uniform in space, the magnet is subject to no net force, although it is subject to a torque.[10]


A wire in the shape of a circle with area A and carrying current I is a magnet, with a magnetic moment of magnitude equal to IA.
Magnetization


Main article: Magnetization


The magnetization of a magnetized material is the local value of its magnetic moment per unit volume, usually denoted M, with unitsA/m.[11] It is a vector field, rather than just a vector (like the magnetic moment), because different areas in a magnet can be magnetized with different directions and strengths (for example, because of domains, see below). A good bar magnet may have a magnetic moment of magnitude 0.1 A•m2 and a volume of 1 cm3, or 1×10−6 m3, and therefore an average magnetization magnitude is 100,000 A/m. Iron can have a magnetization of around a million amperes per meter. Such a large value explains why iron magnets are so effective at producing magnetic fields.
Modelling magnets







Field of a cylindrical bar magnet calculated with Ampère's model


See also: Two definitions of moment


Two different models exist for magnets: magnetic poles and atomic currents.


Although for many purposes it is convenient to think of a magnet as having distinct north and south magnetic poles, the concept of poles should not be taken literally: it is merely a way of referring to the two different ends of a magnet. The magnet does not have distinct north or south particles on opposing sides. If a bar magnet is broken into two pieces, in an attempt to separate the north and south poles, the result will be two bar magnets, each of which has both a north and south pole. However, a version of the magnetic-pole approach is used by professional magneticians to design permanent magnets.[citation needed] In this approach, the divergence of the magnetization ∇•M inside a magnet and the surface normal componentM•n are treated as a distribution of magnetic monopoles. This is a mathematical convenience and does not imply that there are actually monopoles in the magnet. If the magnetic-pole distribution is known, then the pole model gives the magnetic field H. Outside the magnet, the field B is proportional to H, while inside the magnetization must be added to H. An extension of this method that allows for internal magnetic charges is used in theories of ferromagnetism.


Another model is the Ampère model, where all magnetization is due to the effect of microscopic, or atomic, circular bound currents, also called Ampèrian currents, throughout the material. For a uniformly magnetized cylindrical bar magnet, the net effect of the microscopic bound currents is to make the magnet behave as if there is a macroscopic sheet of electric current flowing around the surface, with local flow direction normal to the cylinder axis.[12] Microscopic currents in atoms inside the material are generally canceled by currents in neighboring atoms, so only the surface makes a net contribution; shaving off the outer layer of a magnet will notdestroy its magnetic field, but will leave a new surface of uncancelled currents from the circular currents throughout the material.[13] Theright-hand rule tells which direction the current flows.
Pole naming conventions


The north pole of a magnet is the pole that, when the magnet is freely suspended, points towards the Earth's North Magnetic Polewhich is located in northern Canada. Since opposite poles (north and south) attract, the Earth's "North Magnetic Pole" is thus actually the south pole of the Earth's magnetic field.[14][15][16][17] As a practical matter, in order to tell which pole of a magnet is north and which is south, it is not necessary to use the Earth's magnetic field at all. For example, one method would be to compare it to anelectromagnet, whose poles can be identified by the right-hand rule. The magnetic field lines of a magnet are considered by convention to emerge from the magnet's north pole and reenter at the south pole.[17]
Magnetic materials


Main article: Magnetism


The term magnet is typically reserved for objects that produce their own persistent magnetic field even in the absence of an applied magnetic field. Only certain classes of materials can do this. Most materials, however, produce a magnetic field in response to an applied magnetic field; a phenomenon known as magnetism. There are several types of magnetism, and all materials exhibit at least one of them.


The overall magnetic behavior of a material can vary widely, depending on the structure of the material, particularly on its electron configuration. Several forms of magnetic behavior have been observed in different materials, including:
Ferromagnetic and ferrimagnetic materials are the ones normally thought of as magnetic; they are attracted to a magnet strongly enough that the attraction can be felt. These materials are the only ones that can retain magnetization and become magnets; a common example is a traditional refrigerator magnet. Ferrimagnetic materials, which include ferrites and the oldest magnetic materials magnetite and lodestone, are similar to but weaker than ferromagnetics. The difference between ferro- and ferrimagnetic materials is related to their microscopic structure, as explained in Magnetism.
Paramagnetic substances, such as platinum, aluminum, and oxygen, are weakly attracted to either pole of a magnet. This attraction is hundreds of thousands of times weaker than that of ferromagnetic materials, so it can only be detected by using sensitive instruments or using extremely strong magnets. Magnetic ferrofluids, although they are made of tiny ferromagnetic particles suspended in liquid, are sometimes considered paramagnetic since they cannot be magnetized.
Diamagnetic means repelled by both poles. Compared to paramagnetic and ferromagnetic substances, diamagnetic substances, such as carbon, copper, water, and plastic, are even more weakly repelled by a magnet. The permeability of diamagnetic materials is less than the permeability of a vacuum. All substances not possessing one of the other types of magnetism are diamagnetic; this includes most substances. Although force on a diamagnetic object from an ordinary magnet is far too weak to be felt, using extremely strong superconducting magnets, diamagnetic objects such as pieces of lead and even mice[18] can be levitated, so they float in mid-air. Superconductors repel magnetic fields from their interior and are strongly diamagnetic.


There are various other types of magnetism, such as spin glass, superparamagnetism, superdiamagnetism, and metamagnetism.
Common uses of magnets







Hard disk drives record data on a thin magnetic coating







Magnetic hand separator for heavy minerals
Magnetic recording media: VHS tapes contain a reel of magnetic tape. The information that makes up the video and sound is encoded on the magnetic coating on the tape. Common audio cassettes also rely on magnetic tape. Similarly, in computers, floppy disks and hard disks record data on a thin magnetic coating.[19]
Credit, debit, and ATM cards: All of these cards have a magnetic strip on one side. This strip encodes the information to contact an individual's financial institution and connect with their account(s).[20]
Common televisions and computer monitors: TV and computer screens containing a cathode ray tube employ an electromagnet to guide electrons to the screen.[21] Plasma screens and LCDs use different technologies.
Speakers and microphones: Most speakers employ a permanent magnet and a current-carrying coil to convert electric energy (the signal) into mechanical energy (movement that creates the sound). The coil is wrapped around a bobbin attached to the speakercone and carries the signal as changing current that interacts with the field of the permanent magnet. The voice coil feels a magnetic force and in response, moves the cone and pressurizes the neighboring air, thus generating sound. Dynamic microphones employ the same concept, but in reverse. A microphone has a diaphragm or membrane attached to a coil of wire. The coil rests inside a specially shaped magnet. When sound vibrates the membrane, the coil is vibrated as well. As the coil moves through the magnetic field, a voltage is induced across the coil. This voltage drives a current in the wire that is characteristic of the original sound.
Electric guitars use magnetic pickups to transduce the vibration of guitar strings into electric current that can then be amplified. This is different from the principle behind the speaker and dynamic microphone because the vibrations are sensed directly by the magnet, and a diaphragm is not employed. The Hammond organ used a similar principle, with rotating tonewheels instead of strings.
Electric motors and generators: Some electric motors rely upon a combination of an electromagnet and a permanent magnet, and, much like loudspeakers, they convert electric energy into mechanical energy. A generator is the reverse: it converts mechanical energy into electric energy by moving a conductor through a magnetic field.
Medicine: Hospitals use magnetic resonance imaging to spot problems in a patient's organs without invasive surgery.
Chemistry: Chemists use nuclear magnetic resonance to characterize synthesized compounds.
Chucks are used in the metalworking field to hold objects. Magnets are also used in other types of fastening devices, such as themagnetic base, the magnetic clamp and the refrigerator magnet.
Compasses: A compass (or mariner's compass) is a magnetized pointer free to align itself with a magnetic field, most commonlyEarth's magnetic field.
Art: Vinyl magnet sheets may be attached to paintings, photographs, and other ornamental articles, allowing them to be attached to refrigerators and other metal surfaces. Objects and paint can be applied directly to the magnet surface to create collage pieces of art. Magnetic art is portable, inexpensive and easy to create. Vinyl magnetic art is not for the refrigerator anymore. Colorful metal magnetic boards, strips, doors, microwave ovens, dishwashers, cars, metal I beams, and any metal surface can be receptive of magnetic vinyl art. Being a relatively new media for art, the creative uses for this material is just beginning.
Science projects: Many topic questions are based on magnets, including the repulsion of current-carrying wires, the effect of temperature, and motors involving magnets.[22]







Magnets have many uses in toys. M-tic uses magnetic rods connected to metal spheres for construction. Note the geodesic pyramid
Toys: Given their ability to counteract the force of gravity at close range, magnets are often employed in children's toys, such as the Magnet Space Wheel and Levitron, to amusing effect.
Magnets can be used to make jewelry. Necklaces and bracelets can have a magnetic clasp, or may be constructed entirely from a linked series of magnets and ferrous beads.
Magnets can pick up magnetic items (iron nails, staples, tacks, paper clips) that are either too small, too hard to reach, or too thin for fingers to hold. Some screwdrivers are magnetized for this purpose.
Magnets can be used in scrap and salvage operations to separate magnetic metals (iron, cobalt, and nickel) from non-magnetic metals (aluminum, non-ferrous alloys, etc.). The same idea can be used in the so-called "magnet test", in which an auto body is inspected with a magnet to detect areas repaired using fiberglass or plastic putty.
Magnetic levitation transport, or maglev, is a form of transportation that suspends, guides and propels vehicles (especially trains) through electromagnetic force. The maximum recorded speed of a maglev train is 581 kilometers per hour (361 mph).
Magnets may be used to serve as a fail-safe device for some cable connections. For example, the power cords of some laptops are magnetic to prevent accidental damage to the port when tripped over. The MagSafepower connection to the Apple MacBook is one such example.
Medical issues and safety


Because human tissues have a very low level of susceptibility to static magnetic fields, there is little mainstream scientific evidence showing a health hazard associated with exposure to static fields. Dynamic magnetic fields may be a different issue, however; correlations between electromagnetic radiation and cancer rates have been postulated due to demographic correlations (seeElectromagnetic radiation and health).


If a ferromagnetic foreign body is present in human tissue, an external magnetic field interacting with it can pose a serious safety risk.[23]


A different type of indirect magnetic health risk exists involving pacemakers. If a pacemaker has been embedded in a patient's chest (usually for the purpose of monitoring and regulating the heart for steady electrically induced beats), care should be taken to keep it away from magnetic fields. It is for this reason that a patient with the device installed cannot be tested with the use of an MRI, which is a magnetic imaging device.


Children sometimes swallow small magnets from toys, and this can be hazardous if two or more magnets are swallowed, as the magnets can pinch or puncture internal tissues; one death has been reported.[24]
Magnetizing ferromagnets


See also: Remanence


Ferromagnetic materials can be magnetized in the following ways:
Heating the object above its Curie temperature, allowing it to cool in a magnetic field and hammering it as it cools. This is the most effective method and is similar to the industrial processes used to create permanent magnets.
Placing the item in an external magnetic field will result in the item retaining some of the magnetism on removal. Vibration has been shown to increase the effect. Ferrous materials aligned with the Earth's magnetic field that are subject to vibration (e.g., frame of a conveyor) have been shown to acquire significant residual magnetism.
Stroking: An existing magnet is moved from one end of the item to the other repeatedly in the same direction.
Demagnetizing ferromagnets


Magnetized ferromagnetic materials can be demagnetized (or degaussed) in the following ways:
Heating a magnet past its Curie temperature; the molecular motion destroys the alignment of the magnetic domains. This always removes all magnetization.
Placing the magnet in an alternating magnetic field with intensity above the material's coercivity and then either slowly drawing the magnet out or slowly decreasing the magnetic field to zero. This is the principle used in commercial demagnetizers to demagnetize tools and erase credit cards and hard disks and degaussing coils used to demagnetize CRTs.
Some demagnetization or reverse magnetization will occur if any part of the magnet is subjected to a reverse field above the magnetic material's coercivity.
Demagnetisation progressively occurs if the magnet is subjected to cyclic fields sufficient to move the magnet away from the linear part on the second quadrant of the B-H curve of the magnetic material (the demagnetisation curve).
Hammering or jarring: the mechanical disturbance tends to randomize the magnetic domains. This will leave some residual magnetization.
Types of permanent magnets







A stack of ferrite magnets
Magnetic metallic elements


Many materials have unpaired electron spins, and the majority of these materials areparamagnetic. When the spins interact with each other in such a way that the spins align spontaneously, the materials are called ferromagnetic (what is often loosely termed as magnetic). Because of the way their regular crystalline atomic structure causes their spins to interact, some metals are ferromagnetic when found in their natural states, as ores. These include iron ore (magnetite or lodestone), cobalt and nickel, as well as the rare earth metalsgadolinium and dysprosium (when at a very low temperature). Such naturally occurring ferromagnets were used in the first experiments with magnetism. Technology has since expanded the availability of magnetic materials to include various man-made products, all based, however, on naturally magnetic elements.
Composites


Ceramic, or ferrite, magnets are made of a sintered composite of powdered iron oxide and barium/strontium carbonate ceramic. Given the low cost of the materials and manufacturing methods, inexpensive magnets (or non-magnetized ferromagnetic cores, for use inelectronic components such as radio antennas, for example) of various shapes can be easily mass-produced. The resulting magnets are non-corroding but brittle and must be treated like other ceramics.


Alnico magnets are made by casting or sintering a combination of aluminium, nickel and cobalt with iron and small amounts of other elements added to enhance the properties of the magnet. Sintering offers superior mechanical characteristics, whereas casting delivers higher magnetic fields and allows for the design of intricate shapes. Alnico magnets resist corrosion and have physical properties more forgiving than ferrite, but not quite as desirable as a metal. Trade names for alloys in this family include: Alni, Alcomax, Hycomax, Columax, and Ticonal.[25]


Injection-molded magnets are a composite of various types of resin and magnetic powders, allowing parts of complex shapes to be manufactured by injection molding. The physical and magnetic properties of the product depend on the raw materials, but are generally lower in magnetic strength and resemble plastics in their physical properties.


Flexible magnets are similar to injection-molded magnets, using a flexible resin or binder such as vinyl, and produced in flat strips, shapes or sheets. These magnets are lower in magnetic strength but can be very flexible, depending on the binder used. Flexible magnets can be used in industrial printers.
Rare-earth magnets







An ovoid-shaped rare-earth magnethanging from another


Main article: Rare-earth magnet


Rare earth (lanthanoid) elements have a partially occupied f electron shell (which can accommodate up to 14 electrons). The spin of these electrons can be aligned, resulting in very strong magnetic fields, and therefore, these elements are used in compact high-strength magnets where their higher price is not a concern. The most common types of rare-earth magnets are samarium-cobalt and neodymium-iron-boron (NIB) magnets.
Single-molecule magnets (SMMs) and single-chain magnets (SCMs)


In the 1990s, it was discovered that certain molecules containing paramagnetic metal ions are capable of storing a magnetic moment at very low temperatures. These are very different from conventional magnets that store information at a magnetic domain level and theoretically could provide a far denser storage medium than conventional magnets. In this direction, research on monolayers of SMMs is currently under way. Very briefly, the two main attributes of an SMM are:
a large ground state spin value (S), which is provided by ferromagnetic or ferrimagnetic coupling between the paramagnetic metal centres
a negative value of the anisotropy of the zero field splitting (D)


Most SMMs contain manganese but can also be found with vanadium, iron, nickel and cobalt clusters. More recently, it has been found that some chain systems can also display a magnetization that persists for long times at higher temperatures. These systems have been called single-chain magnets.
Nano-structured magnets


Some nano-structured materials exhibit energy waves, called magnons, that coalesce into a common ground state in the manner of aBose-Einstein condensate.[26][27]
Costs


The current cheapest permanent magnets, allowing for field strengths, are flexible and ceramic magnets, but these are also among the weakest types. The ferrite magnets are mainly low-cost magnets since they are made from cheap raw materials- iron oxide and Ba- or Sr-carbonate. However, a new low cost magnet- Mn-Al alloy[citation needed] has been developed and is now dominating the low-cost magnets field. It has a higher saturation magnetization than the ferrite magnets. It also has more favorable temperature coefficients, although it can be thermally unstable. Neodymium-iron-boron (NIB) magnets are among the strongest. These cost more per kilogram than most other magnetic materials but, owing to their intense field, are smaller and cheaper in many applications.[28]
Temperature


Temperature sensitivity varies, but when a magnet is heated to a temperature known as the Curie point, it loses all of its magnetism, even after cooling below that temperature. The magnets can often be remagnetized, however.


Additionally, some magnets are brittle and can fracture at high temperatures.


The maximum usable temperature is highest for alnico magnets at over 540 °C (1,000 °F), around 300 °C (570 °F) for ferrite and SmCo, about 140 °C (280 °F) for NIB and lower for flexible ceramics, but the exact numbers depend on the grade of material.
Electromagnets


Main article: Electromagnet


An electromagnet, in its simplest form, is a wire that has been coiled into one or more loops, known as a solenoid. When electric current flows through the wire, a magnetic field is generated. It is concentrated near (and especially inside) the coil, and its field lines are very similar to those of a magnet. The orientation of this effective magnet is determined by the right hand rule. The magnetic moment and the magnetic field of the electromagnet are proportional to the number of loops of wire, to the cross-section of each loop, and to the current passing through the wire.[29]


If the coil of wire is wrapped around a material with no special magnetic properties (e.g., cardboard), it will tend to generate a very weak field. However, if it is wrapped around a soft ferromagnetic material, such as an iron nail, then the net field produced can result in a several hundred- to thousandfold increase of field strength.


Uses for electromagnets include particle accelerators, electric motors, junkyard cranes, and magnetic resonance imaging machines. Some applications involve configurations more than a simple magnetic dipole; for example, quadrupole and sextupole magnets are used to focus particle beams.
Units and calculations


Main article: Magnetostatics


For most engineering applications, MKS (rationalized) or SI (Système International) units are commonly used. Two other sets of units,Gaussian and CGS-EMU, are the same for magnetic properties and are commonly used in physics.


In all units, it is convenient to employ two types of magnetic field, B and H, as well as the magnetization M, defined as the magnetic moment per unit volume.
The magnetic induction field B is given in SI units of teslas (T). B is the magnetic field whose time variation produces, by Faraday's Law, circulating electric fields (which the power companies sell). B also produces a deflection force on moving charged particles (as in TV tubes). The tesla is equivalent to the magnetic flux (in webers) per unit area (in meters squared), thus giving B the unit of a flux density. In CGS, the unit of B is the gauss (G). One tesla equals 104 G.
The magnetic field H is given in SI units of ampere-turns per meter (A-turn/m). The turns appears because when H is produced by a current-carrying wire, its value is proportional to the number of turns of that wire. In CGS, the unit of H is the oersted (Oe). One A-turn/m equals 4π×10−3 Oe.
The magnetization M is given in SI units of amperes per meter (A/m). In CGS, the unit of M is the oersted (Oe). One A/m equals 10−3 emu/cm3. A good permanent magnet can have a magnetization as large as a million amperes per meter.
In SI units, the relation B = μ0(H + M) holds, where μ0 is the permeability of space, which equals 4π×10−7 T•m/A. In CGS, it is written as B = H + 4πM. (The pole approach gives μ0H in SI units. A μ0M term in SI must then supplement this μ0H to give the correct field within B, the magnet. It will agree with the field B calculated using Ampèrian currents]


Materials that are not permanent magnets usually satisfy the relation M = χH in SI, where χ is the (dimensionless) magnetic susceptibility. Most non-magnetic materials have a relatively small χ (on the order of a millionth), but soft magnets can have χ on the order of hundreds or thousands. For materials satisfying M = χH, we can also write B = μ0(1 + χ)H = μ0μrH = μH, where μr = 1 + χ is the (dimensionless) relative permeability and μ =μ0μr is the magnetic permeability. Both hard and soft magnets have a more complex, history-dependent, behavior described by what are called hysteresis loops, which give either B vs. H or M vs. H. In CGS, M = χH, butχSI = 4πχCGS, and μ = μr.


Caution: in part because there are not enough Roman and Greek symbols, there is no commonly agreed-upon symbol for magnetic pole strength and magnetic moment. The symbol m has been used for both pole strength (unit A•m, where here the upright m is for meter) and for magnetic moment (unit A•m2). The symbol μ has been used in some texts for magnetic permeability and in other texts for magnetic moment. We will use μ for magnetic permeability and m for magnetic moment. For pole strength, we will employ qm. For a bar magnet of cross-section A with uniform magnetization M along its axis, the pole strength is given by qm = MA, so that M can be thought of as a pole strength per unit area.
Fields of a magnet


Far away from a magnet, the magnetic field created by that magnet is almost always described (to a good approximation) by a dipole field characterized by its total magnetic moment. This is true regardless of the shape of the magnet, so long as the magnetic moment is non-zero. One characteristic of a dipole field is that the strength of the field falls off inversely with the cube of the distance from the magnet's center.


Closer to the magnet, the magnetic field becomes more complicated and more dependent on the detailed shape and magnetization of the magnet. Formally, the field can be expressed as a multipole expansion: A dipole field, plus a quadrupole field, plus an octupole field, etc.


At close range, many different fields are possible. For example, for a long, skinny bar magnet with its north pole at one end and south pole at the other, the magnetic field near either end falls off inversely with the square of the distance from that pole.
Calculating the magnetic force


Main article: force between magnets
Pull force of a single magnet


The strength of a given magnet is sometimes given in terms of its pull force— its ability to move (push/ pull) other objects. The pull force exerted by either an electromagnet or a permanent magnet at the "air gap" (i.e., the point in space where the magnet ends) is given by the Maxwell equation:[30]

,


where

F is force (SI unit: newton)

A is the cross section of the area of the pole in square meters

B is the magnetic induction exerted by the magnet


Therefore, if a magnet is acting vertically, it can lift a mass m in kilograms given by the simple equation:

.
Force between two magnetic poles


Further information: Magnetic moment#Forces between two magnetic dipoles


Classically, the force between two magnetic poles is given by:[31]




where

F is force (SI unit: newton)

qm1 and qm2 are the magnitudes of magnetic poles (SI unit: ampere-meter)

μ is the permeability of the intervening medium (SI unit: tesla meter per ampere, henry per meter or newton per ampere squared)

r is the separation (SI unit: meter).


The pole description is useful to the engineers designing real-world magnets, but real magnets have a pole distribution more complex than a single north and south. Therefore, implementation of the pole idea is not simple. In some cases, one of the more complex formulae given below will be more useful.
Force between two nearby magnetized surfaces of area A


The mechanical force between two nearby magnetized surfaces can be calculated with the following equation. The equation is valid only for cases in which the effect of fringing is negligible and the volume of the air gap is much smaller than that of the magnetized material:[32][33]




where:

A is the area of each surface, in m2

H is their magnetizing field, in A/m

μ0 is the permeability of space, which equals 4π×10−7 T•m/A

B is the flux density, in T.
Force between two bar magnets


The force between two identical cylindrical bar magnets placed end to end is given by:[32]




where:

B0 is the magnetic flux density very close to each pole, in T,

A is the area of each pole, in m2,

L is the length of each magnet, in m,

R is the radius of each magnet, in m, and

x is the separation between the two magnets, in m.

relates the flux density at the pole to the magnetization of the magnet.


Note that all these formulations are based on Gilbert's model, which is usable in relatively great distances. In other models (e.g., Ampère's model), a more complicated formulation is used that sometimes cannot be solved analytically. In these cases, numerical methods must be used.
Force between two cylindrical magnets


For two cylindrical magnets with radius and height , with their magnetic dipole aligned, the force can be well approximated (even at distances of the order of ) by,[34]




where is the magnetization of the magnets and is the gap between the magnets. In disagreement to the statement in the previous section, a measurement of the magnetic flux density very close to the magnet is related to by the formula




The effective magnetic dipole can be written as




Where is the volume of the magnet. For a cylinder, this is .


When , the point dipole approximation is obtained,




which matches the expression of the force between two magnetic dipoles.






source : http://en.wikipedia.org/wiki/Magnet

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