Required Practical 4: Current/PD

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

  Current voltage characteristics of circuit components
• 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 and variable resistor
  • 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 passing through zero on the graph indicate?

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

  A resistor where current is proportional to voltage
• What happens to the graph if the resistor's temperature increases?

  The graph will not have a linear 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 forward and reverse battery direction
• Why is the current not proportional to the potential difference in a filament lamp?

  Increased temperature raises resistance
• What is the effect of changing the direction of potential difference in a filament lamp experiment?

  • The graph shape remains the same
  • Current still increases with potential difference
  • Resistance changes due to temperature
• What is the setup for investigating a diode's characteristics?

  • Diode in the circuit with an extra resistor
  • Use a sensitive ammeter (milliammeter)
  • Adjust variable resistor and record readings
• Why is an extra resistor used in the diode circuit?

  To protect the diode from high current
• What type of ammeter is used for measuring current in a diode circuit?

  Milliammeter
• What happens to the current when the potential difference is around 0.6 to 0.7 volts in a diode?

  Current rises sharply beyond this point
• What occurs in a diode when the potential difference is reversed?

  No current flows due to high resistance
• What is a key feature of diodes in terms of current flow?

  • Current flows only in one direction
  • High resistance in reverse direction
  • Sensitive to high current