Required Practical 4: Current/PD Characteristics

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

  Investigate current voltage characteristics
• What does the investigation focus on regarding circuit components?

  How current depends on potential difference
• What is the setup for investigating a resistor's characteristics?

  • Battery connected to a resistor
  • Resistor in series with an ammeter
  • Variable resistor included
  • Voltmeter in parallel across the resistor
• What do you use to read the potential difference across the resistor?

  Voltmeter
• What do you use to read the current through the resistor?

  Ammeter
• What should you do after recording the initial readings?

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

  Potential difference direction reverses
• What does a straight line graph through zero indicate for a resistor?

  Current is directly proportional to potential difference
• What is an ohmic conductor?

  A resistor that follows Ohm's law
• What happens to the graph shape if the resistor's temperature increases?

  The graph will not have a straight line shape
• What is the procedure for investigating a filament lamp's characteristics?

  • Replace resistor with filament lamp
  • Adjust variable resistor and record readings
  • Repeat for both battery directions
  • Analyze the resulting graph
• Why is the current not proportional to the potential difference in a filament lamp?

  Increased temperature raises resistance
• What is the setup for investigating a diode's characteristics?

  • Diode included in the circuit
  • Extra resistor to limit current
  • Sensitive ammeter (milliammeter) used
  • Record readings for both battery directions
• What happens to the current when the potential difference is around 0.6 to 0.7 volts in a diode?

  Current begins to rise sharply
• What occurs in a diode when the potential difference is reversed?

  No current flows due to high resistance
• What type of ammeter is used for measuring low currents in a diode?

  Milliammeter
• What should you avoid to maintain accurate results in the resistor experiment?

  • Do not leave the circuit connected too long
  • Prevent temperature increase in the resistor
• Where can you find more questions on this required practical?

  In the vision workbook