GCSE Physics - V = IR Equation

• What is the equation that relates voltage, current, and resistance?

  v = ir
• What does the equation v = ir represent?


  Voltage equals current times resistance
• If a circuit has a current of 4 amps and a resistance of 2 ohms, what is the voltage?

  8 volts
• How do you find the resistance if you have a 24 volt battery producing 8 amps?

  Use r = v / i
• What is the resistance when using a 24 volt battery and 8 amps?

  3 ohms
• What happens to current when voltage increases while resistance remains constant?

  Current increases proportionally
• What does a graph of current against potential difference show when resistance is constant?

  It shows a straight line
• What does a steeper line on a current versus potential difference graph indicate?

  Less resistance in the circuit
• What happens to resistance if the temperature increases?

  Resistance increases
• What is the effect of higher currents on wires over time?

  Wires heat up
• What do filament lamps contain that emits light when heated?

  A thin metal filament
• How does the resistance of a filament lamp change as current increases?

  Resistance increases due to heating
• What is the characteristic of diodes regarding current flow?

  They allow current to flow in one direction
• What happens to current in a diode when the potential difference is negative?

  No current flows
• What is the resistance of a diode in the reverse direction?

  Very high resistance