Question 1: Define potential difference (PD) and explain its significance in an electrical circuit.

Answer: Potential difference is the work done per unit charge to move a charge between two points in a circuit. It indicates the energy supplied by the source to drive current through the circuit.

Question 2: Describe how potential difference affects the current flowing through a resistor.

Answer: An increase in potential difference across a resistor causes an increase in current, according to Ohm's Law. Conversely, decreasing PD reduces current flow.

Question 1: A circuit has a resistance of 10 Ω and a current of 2 A flows through it. Calculate the potential difference across the resistor using Ohm's Law (V = IR).

Answer: V = IR = 2 A × 10 Ω = 20 V

Question 2: A 12 V power supply is connected to a circuit with a resistance of 4 Ω. What is the current flowing through the circuit?

Answer: I = V / R = 12 V / 4 Ω = 3 A

Question 1: Describe a simple experiment to measure the potential difference across a resistor in a circuit. Include the variables you would control and measure, and mention safety precautions.

Answer: Set up a circuit with a power supply, resistor, and voltmeter connected in parallel across the resistor. Control the voltage supplied and record the reading on the voltmeter. Measure the current using an ammeter if needed. Ensure all connections are secure and avoid touching live wires to prevent shocks.

Question 1: A series circuit with three resistors (R1 = 5 Ω, R2 = 10 Ω, R3 = 15 Ω) is powered by a 30 V supply. The voltage across each resistor is measured and found to be 8 V, 12 V, and 10 V respectively. Explain whether these measurements are consistent with the resistances and the total voltage supplied. Justify your answer.

Answer: In a series circuit, the sum of individual voltages across resistors should equal the total supply voltage (30 V). Here, 8 V + 12 V + 10 V = 30 V, which matches the supply. The voltages are proportional to resistance; R1 has the lowest voltage, R2 medium, R3 the highest, consistent with their resistance values. Therefore, the data is consistent with Ohm's Law and the resistances.

Question 1: Explain how potential difference and resistance determine the current in a circuit. Use appropriate scientific terminology in your answer. (6 marks)

Answer: Potential difference provides the energy to move charges through a circuit, while resistance opposes this movement. According to Ohm's Law (V = IR), the current is directly proportional to the potential difference and inversely proportional to resistance. Therefore, increasing PD increases current, whereas increasing resistance decreases current, assuming all other factors remain constant.

Question 1: Explain how potential difference is utilised in household electrical systems and why it is important for safety and efficiency.

Answer: Household electrical systems supply a standard potential difference (e.g., 230 V in the UK) to ensure appliances operate efficiently and safely. Proper PD ensures devices function correctly without damage, and consistent voltage levels prevent electrical shocks or fires. Safety devices like fuses and circuit breakers help manage PD to prevent overloads.