Electricity

Static electricity

charge 电荷

electron 电子 (-) 能动 Atom

• nucleus 荷
  • neutron 中子
  • proton 质子

coulomb 库伦

Insulator 绝缘体

Friction

insulated conductor

导体接地消电

如果带正电，会把负电吸回来

如果带负电，会把负电退回去

unlike charges attract 异性相吸

like charges repel 同性相斥

• repulsion
• repulsion
• attraction
• attraction neutrally charged
• attraction

electric field

正电 电场线朝外

负电 电场线朝内

电场线表示正电荷的方向

电场强度随随电场距离增大而减小

平行电极板 parallel charged plate

电流 charge

1. conventional flow
2. flow of electron

formular

• Difinition of charge
• Difinition of Potential difference
• Difinition of resistance : law
• Difinition of Emf
• Resistance , is resistivity 电阻率

Emf : electronmotiveforce 电动势

Resistor

• ohmic resistor
  • L-V graph was a straight line
    • is not gradient, R =
• non-ohmic
  • L-V graph was a curve

电路

元器件

1. 电源
   1. DC : direct current 直流电
      1. cell (dry) 干电池
   2. AC : Alternating current 交流电 o~o
2. resister
   1. fixed resistor
   2. varriable resistor
   3. potential divider
   4. thermister 热敏电阻
   5. Light Dependent Resister (LDR) 光敏电阻
3. 仪表
   1. V
   2. A
4. fuse

串联和并联

• parallel 并联
  • is inversely proportional to
• serirs 串联
  • is directly proportional to
  • 2. if then

Practical electricity

unit of electricity

British standard soket :

	earth (yellow & green, 230V)
neutral (blue, 0 pd.)		live (brown or red, high pd.)

Safe

1. metal casing
2. fuse
   • fuse rating (额定电流)
     • , ,
3. double insulation
4. Cannot use electric at water
5. Exposed wire
6. overload, overheat