p1 current / pd

• What should you be able to describe by the end of the video?

  Current voltage characteristics of circuit components
• What is the procedure to investigate current voltage characteristics of a resistor?

  • Connect a battery to a resistor
  • Use an ammeter in series
  • Use a voltmeter in parallel
  • Record potential difference and current
  • Adjust variable resistor and repeat
  • Switch battery direction and repeat
  • Plot current against potential difference
• What does the graph of current against potential difference for a resistor look like?

  A straight line passing through zero
• What does it mean if a resistor is described as an ohmic conductor?

  Current is directly proportional to potential difference
• What happens to the graph if the temperature of the resistor increases?

  The graph will not have a straight line shape
• What is the procedure to investigate current voltage characteristics of a filament lamp?

  • Replace the resistor with a filament lamp
  • Adjust variable resistor and record values
  • Repeat with battery in both directions
  • Plot current against potential difference
• What does the graph of current against potential difference for a filament lamp look like?

  It is not proportional to potential difference
• Why does the current not remain proportional to potential difference in a filament lamp?

  Increased temperature causes resistance to increase
• What is the procedure to investigate current voltage characteristics of a diode?

  • Use a diode in the circuit
  • Include an extra resistor to limit current
  • Use a sensitive ammeter (milliammeter)
  • Adjust variable resistor and record values
  • Repeat with battery in both directions
• What does the graph of current against potential difference for a diode look like?

  Current only flows after 0.6-0.7 volts
• What happens to the current when the potential difference is reversed in a diode?

  No current flows due to high resistance
• What type of ammeter is used when measuring current through a diode?

  A milliammeter
• What should you avoid doing to prevent the resistor from heating up during the experiment?

  • Do not leave the circuit connected for too long
• Where can you find more questions on this required practical?

  • In the vision workbook linked in the video