RP: investigating current - voltage graphs

• What are the two types of electrical current mentioned?

  Direct and alternating current
• What does the potential difference (or voltage) measure in a circuit?

  It measures the energy given to the charge carriers in a circuit
• What are the units of potential difference?

  Volts (V)
• What is the purpose of a resistor in an electrical circuit?

  To restrict the flow of electrical charge
• What is a fixed-value resistor?

  A resistor that does not change its resistance
• What is a diode?

  An electrical device that allows current to flow in one direction only
• What is the aim of the experiment described in the study material?

  To investigate the relationship between current and potential difference for a resistor, bulb, and diode
• What should be done before starting the experiment with the power supply?

  The power supply should be set to zero
• How do you alter the potential difference in the experiment?

  By using the variable resistor
• What is the relationship between potential difference and current for a fixed resistor?

  The potential difference is directly proportional to the current
• What does Ohm's Law state?

  The current (I) flowing through a resistor (R) is directly proportional to the voltage (V) across the resistor
• What is the resistance measured in?

  Ohms (Ω)
• How does the current behave in a filament bulb compared to a fixed resistor?

  The current does not increase as fast as the potential difference in a filament bulb
• What happens to the resistance of a filament bulb as the potential difference increases?

  The resistance of the bulb increases as the potential difference increases
• What is a semiconductor diode?

  A diode that only allows current to flow in one direction
• What occurs when a diode is reverse-biased?

  No current will flow as the diode’s resistance remains very large
• What happens to the diode's resistance at higher potential differences when it is forward-biased?

  The resistance quickly drops and current begins to flow
• What is a hazard associated with the experiment involving resistance wire?

  Heating of the resistance wire
• What control measure should be taken to prevent burns from the resistance wire?

  Do not touch the resistance wire while the circuits are connected and allow it time to cool
• What are the steps to investigate the relationship between current and potential difference for a resistor, bulb, and diode?

  1. Connect the circuit as shown in the diagram.
  2. Set the power supply to zero.
  3. Record readings on the voltmeter and ammeter.
  4. Use the variable resistor to alter the potential difference.
  5. Record new readings.
  6. Repeat the process, increasing the potential difference slightly.
  7. Reverse the power supply connections and repeat.
  8. Plot a graph of current against potential difference for each component.
• What are the results for a 10 Ohm fixed resistor in terms of potential difference and current?

  • Potential difference (V) and Current (A) relationship:
  • 0.5 V = 0.05 A
  • 1.0 V = 0.10 A
  • 1.5 V = 0.15 A
  • 2.0 V = 0.20 A
• What are the results for a filament bulb in terms of potential difference and current?

  • Potential difference (V) and Current (A) relationship:
  • 0.5 V = 0.10 A
  • 1.0 V = 0.20 A
  • 1.5 V = 0.35 A
  • 2.0 V = 0.50 A
  • 10.0 V = 1.50 A
• What are the hazards and control measures in the experiment?

  • Hazards:
  • Heating of the resistance wire
  • Control Measures:
  • Do not touch the resistance wire while circuits are connected
  • Allow it time to cool