Current / PD Characteristics

• What should you be able to describe by the end of the video on current voltage characteristics?

  How to investigate the current voltage characteristics of circuit components
• What is the purpose of the practical investigation described in the video?

  • To understand the relationship between current and potential difference
  • To learn how to measure these values using specific equipment
  • To plot graphs based on the collected data
• What components are included in the circuit used to investigate a resistor?

  A battery, resistor, ammeter, variable resistor, and voltmeter
• How do you measure the potential difference across the resistor?

  By using a voltmeter connected in parallel across the resistor
• What do you do after recording the initial readings of potential difference and current?

  Adjust the variable resistor and record the new readings
• What happens when you switch the direction of the battery?

  The direction of the potential difference reverses
• What does the graph of current against potential difference look like for a resistor?

  A straight line passing through zero
• What does it mean if the current through a resistor is directly proportional to the potential difference?

  The resistor is an ohmic conductor
• What happens to the graph if the temperature of the resistor increases?

  The graph will not have a straight line shape
• How does the experiment change when using a filament lamp instead of a resistor?

  • The current is not proportional to the potential difference
  • Increased temperature causes resistance to increase
  • The graph shape changes compared to that of a resistor
• What is the effect of increasing current on the filament lamp?

  The temperature of the filament lamp increases
• What is the shape of the graph when investigating a filament lamp?

  The graph is not a straight line
• What is the setup for investigating a diode in the circuit?

  • A diode is included in the circuit
  • An extra resistor is added to protect the diode
  • A sensitive ammeter (milliammeter) is used
• What happens to the current when the potential difference is reversed in a diode?

  The current does not flow due to high resistance
• At what potential difference does the current start to flow in a diode?

  Approximately 0.6 to 0.7 volts
• What is the purpose of the extra resistor in the diode circuit?

  To keep the current relatively low and protect the diode
• What are the key differences in the current-voltage characteristics of a resistor, filament lamp, and diode?

  • Resistor: Current is directly proportional to potential difference (ohmic)
  • Filament lamp: Current is not proportional due to temperature effects
  • Diode: Current flows only in one direction after a threshold voltage