V = IR Equation & Current/Potential Difference Graphs

• 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 resistance if you have a voltage of 24 volts and a current of 8 amps?

  r = v / i
• What is the resistance when using a 24 volt battery producing 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 negative part of the current versus potential difference graph indicate?

  Voltage and current are negative
• Why do circuits with only wires or resistors produce straight lines on the graph?

  Resistance stays constant throughout
• How does the steepness of the line on a current versus potential difference graph change with different resistors?

  A bigger resistor has a less steep line
• What does a smaller resistor require to drive a large current?

  A small potential difference
• What happens to resistance if the temperature increases?

  Resistance increases
• What is the function of a filament lamp?

  It emits light when current flows
• How does the resistance of a filament lamp change as current increases?

  Resistance increases due to heating
• What is the behavior of diodes in terms of current flow?

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

  No current flows
• What are the key characteristics of current versus potential difference graphs for resistors and wires?

  • Straight lines indicate constant resistance
  • Steeper lines indicate lower resistance
  • Less steep lines indicate higher resistance
• What are the differences between filament lamps and diodes in terms of current flow?

  Filament Lamps:

  • Emit light when current flows
  • Resistance increases with current

  
  

  Diodes:

  • Allow current in one direction only
  • Block current in the reverse direction