current/ P.D characteristics required practical

• Investigating the current-voltage characteristics of circuit components

  1. Use a circuit with a battery, wires, a resistor, an ammeter, a variable resistor, and a voltmeter

  2. Measure the potential difference across the resistor using the voltmeter

  3. Measure the current through the resistor using the ammeter

  4. Record the potential difference and current values in a table

  5. Adjust the variable resistor to get a range of readings

  6. Reverse the direction of the battery and repeat the measurements
• Resistor


  • Current through the resistor is directly proportional to the potential difference across it
  • Relationship holds true even when the direction of the potential difference is reversed
  • Temperature of the resistor must be kept constant
• Filament lamp


  • Current is not proportional to the potential difference
  • As current increases, the temperature of the filament increases, causing the resistance to increase
  • Relationship holds true even when the direction of the potential difference is reversed
• Diode


  • Current only flows when the potential difference is around 0.6-0.7 volts in the forward direction
  • No current flows when the potential difference is reversed
  • An extra resistor is needed to protect the diode from high currents
• A sensitive ammeter (milliammeter) is needed to measure the low current through the diode