Potential Difference Graphs

• 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 of current?

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

  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 straight lines
• 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
• Why do filament lamps have a less steep curve at higher currents?

  Resistance increases due to heating
• What do diodes allow in terms of current flow?

  Current flows in one direction only
• What happens to current when the potential difference is negative in a diode?

  No current flows
• What are the key characteristics of filament lamps and diodes in current versus potential difference graphs?

  • Filament lamps:
  • Resistance increases with current
  • Curve gets less steep at higher currents
  • Diodes:
  • Allow current in one direction
  • No current flows when potential difference is negative
• What factors affect the shape of current versus potential difference graphs?

  • Resistance of components
  • Temperature of the circuit
  • Type of material used (e.g., wire or resistor)