Current, potential difference and resistance

• Current


  Flow of electrical charge
• Potential Difference


  how much electrical work is done by a cell
• Charge


  Amount of electricity travelling in a circuit
• Changing Current


  • Change the potential difference of the cells
  • Add more components
• Adding more components


  Ammeter - Set up in series with components

  Voltmeter - set up in parallel to components
• Resistance


  A measurement of how much current flow is reduced

  • The higher the resistance the more difficult it is for current to flow
  • Increasing resistance - reduces current
  • Increasing voltage - increases current
• Ohmic conduct


  At a constant temperature, current is directly proportional to the potential difference across the resistor
• Filament lamp


  As current increases, the resistance increases. The temperature increases as current flows
• Diode


  Current flows when potential difference flows forwards, very high resistance in reverse
• Thermistor


  Resistance varies with temperature

  Resistance decreases as temperature increases
• LDR


  Resistance varies with light intensity

  Resistance decreases as light increases
• Cell

  Store of chemical energy
• Battery


  Two or more cells in series
• Switch


  Breaks circuit turning current off
• Lamp


  Lights when current flows
• Ammeter


  Measures current
• Volt meter


  Measures potential difference
• Diode


  Current flows one way
• LED


  Emits light when current flows
• Fuse


  Melts when current is too high
• Resistor


  Affects the size of current flowing
• Variable Resistor


  Allows current to be varied
• Thermistor


  Resistance low at high temperature