Question 1: Define Potential Difference (PD) in an electrical circuit.

Answer: Potential Difference (PD) is the work done per unit charge to move a charge between two points in a circuit, measured in volts (V).

Question 2: Explain how potential difference affects the flow of current in a circuit.

Answer: A higher potential difference increases the energy supplied to charges, causing a greater current flow, provided the circuit components allow it.

Question 1: What is the SI unit of potential difference?

Answer: Volt (V)

Question 2: Describe the role of a resistor in an electrical circuit with respect to potential difference.

Answer: A resistor limits the flow of current and causes a voltage drop across itself, thereby affecting the potential difference in the circuit.

Question 1: A circuit has a current of 2 amperes flowing through a resistor. The voltage across the resistor is 12 volts. Calculate the resistance of the resistor using Ohm’s law.

Answer: Resistance R = V / I = 12 V / 2 A = 6 ohms

Question 2: A battery supplies a potential difference of 9 volts to a circuit with a resistance of 3 ohms. Calculate the current flowing through the circuit.

Answer: Current I = V / R = 9 V / 3 Ω = 3 amperes

Question 3: In a circuit, if the current is 0.5 A and the resistance is 20 Ω, what is the potential difference across the resistor?

Answer: V = I × R = 0.5 A × 20 Ω = 10 volts

Question 1: Identify three variables that need to be controlled when measuring potential difference in a circuit experiment.

Answer: Type of resistor, circuit connections, and temperature.

Question 2: List two safety precautions to observe when working with electrical circuits involving potential difference.

Answer: Ensure the circuit is switched off before making adjustments and avoid contact with live wires.

Question 1: A device has a potential difference of 15 volts and draws a current of 0.75 amperes. Calculate the power consumed by the device.

Answer: Power P = V × I = 15 V × 0.75 A = 11.25 watts

Question 2: If a circuit with a resistance of 10 ohms has a potential difference of 20 volts, explain what happens to the current if the resistance increases to 20 ohms, assuming the same voltage source.

Answer: According to Ohm’s law (I = V / R), if the resistance increases from 10 Ω to 20 Ω with the same voltage of 20 V, the current will decrease from 2 A to 1 A, halving the current flow.

Question 1: Explain how potential difference is used in household electrical systems to ensure appliances operate correctly.

Answer: Household electrical systems supply a standard potential difference (230 V in the UK), providing consistent energy to operate appliances efficiently and safely.

Question 2: Describe one technological advancement that relies on precise control of potential difference.

Answer: Microprocessors in computers rely on precise control of potential difference to function correctly, enabling accurate data processing.