P2

• Standard circuit diagram symbols

  • Switch (open)
  • LED (light emitting diode)
  • Switch (closed)
  • Lamp (bulb)
  • Cell
  • Fuse
  • Battery
  • Voltmeter
  • Diode
  • Ammeter
  • Resistor
  • Thermistor
  • Variable resistor
  • LDR (light-dependent resistor)
• Charge flow


  Current x time
• Potential difference


  Current x resistance
• IV characteristics and required practical

  • Ohmic resistor
  • Filament bulb
  • Diode
  • LDR
  • Thermistor
  • Resistance in a wire
• Series Circuits


  • The current does not split and is the same everywhere
  • The voltage is shared
  • RTOTAL = R1 + R2 + R3 ...
• Parallel Circuits


  • The current splits at the junction
  • The voltage is not shared
• Mains electricity keywords


  • Earth wire
  • Fuse
  • Neutral wire
  • Live wire (230v)
  • Cable grip
  • Double insulated cable
  • Alternating current (AC)
  • Direct current (DC)
• Power


  Current^2 x resistance
• Power


  Current x potential difference
• Energy transferred


  Charge flow x potential difference
• Symbols and their units

  • V (Potential difference, Volts)
  • I (Current, Amps)
  • R (Resistance, Ohms)
  • Q (Charge, Coulombs)
  • P (Power, Watts)
  • E (Energy, Joules)
• The National grid


  1. Step up transformer (Increase the voltage of the AC)

  2. High voltage transmission cables (High voltage reduces energy loss)

  3. Step down transformer (Decreases the voltage of the AC)
• Insulator


  Material which holds electrical charge and does not conduct it
• Friction


  Force which transfers electrons from one insulator to the other
• Electrons


  Negatively charged particles in atoms. They are the only charges that can move
• Electrostatic force


  The force between two charges
• Van der Graaff generator

  Machine used to generate static electricity
• Electrostatic force rules


  • - and - charges repel
  • + and - charges attract
  • + and + charges repel