Question 1: Define electrical power in the context of mains electricity.

Answer: Electrical power is the rate at which electrical energy is transferred or converted in a circuit, measured in watts (W).

Question 2: Explain how the power dissipated in a resistor can be calculated using voltage and current.

Answer: Power can be calculated using the formulas P = V × I, where P is power in watts, V is voltage in volts, and I is current in amperes.

Question 1: A kettle operates at a voltage of 230 V and a current of 10 A. Calculate its power consumption in watts.

Answer: 2300 W

Question 2: A household appliance uses 1500 W of power and runs for 3 hours. How much energy does it consume in kilowatt-hours?

Answer: 4.5 kWh

Question 1: Describe a basic experimental setup to measure the power consumption of an electrical device using a multimeter and a wattmeter.

Answer: The setup involves connecting the device in series with a multimeter to measure current, and in parallel with a wattmeter to measure voltage and power. Ensure the circuit is correctly insulated, and the wattmeter is rated for the expected power levels. Safety precautions include turning off power before connecting or disconnecting equipment and avoiding contact with live parts.

Question 2: Identify two variables that affect the power consumption of an electrical appliance and explain how they influence it.

Answer: Voltage and current affect power; increasing either increases the power consumed by the appliance.

Question 1: A dishwasher uses 2 kW of power when operating. If it runs for 1.5 hours per cycle, how much energy does it consume per cycle? Explain your reasoning.

Answer: It consumes 3 kWh per cycle because energy (kWh) = power (kW) × time (hours). So, 2 kW × 1.5 hours = 3 kWh.

Question 1: A 60 W light bulb is connected to a 230 V mains supply. Calculate the current flowing through the bulb. Show all working.

Answer: I = P / V = 60 W / 230 V ≈ 0.26 A

Question 2: Explain how the concept of power relates to energy consumption in household appliances, and why understanding power ratings is important for consumers.

Answer: Power indicates the rate at which an appliance uses electrical energy. Higher power ratings mean the appliance consumes more energy in a given time, leading to higher electricity bills. Understanding power ratings helps consumers choose energy-efficient appliances and manage their energy use effectively, reducing environmental impact and cost.

Question 1: In the industry, engineers select wiring and circuit components based on the power ratings of devices. Explain why knowing the power consumption of these devices is essential for safety and efficiency.

Answer: Knowing power consumption ensures wiring and components can handle the load safely, preventing overheating or fires, and helps optimise energy use to improve efficiency.