Magnetism

electromagnetism

• magnetic 可磁化
  • Iron Steel
  • Nikel
  • Cobalt
• non-magetic 不可磁化
  • Copper
  • Silver
  • Gold
  • Aluminium
  • Calcium

magnetic domain 小磁场

磁铁 magnetic domain one direction

position	direction
inner	S N
outer	N S

Induction

• unlike poles attract

• like poles repels

• 怎样磁化

  1. Stroke
  2. electro-magnet (dc)

• 消磁

  1. heat
  2. hit
  3. ac
     1. 东西方向，不然会被地球磁场影响
     2. 一点一点的拿出来

1. permenant (hard) 硬磁铁
   • steel
2. temporary (Iron) 软磁铁
   • Iron

电磁

右手螺旋定则 (right hand grip rule)

• Solenoid
  1. 大拇指向 n 磁力

1. magnetic metal / magnet
2. 电流
3. 运动中的带电粒子 (moving charged particles)

Fleming left rule

• repels
• repels

电磁感应

法拉第 Faraday (magnittude)

楞次 Lenze (direction)

induce current will opposite the change in magnetic flux

来据去留