Question 1: Define electrical power and state its SI unit.

Answer: Electrical power is the rate at which electrical energy is converted into other forms of energy, measured in watts (W).

Question 2: Explain how voltage and current relate to electrical power.

Answer: Electrical power depends on voltage and current; higher voltage or current increases power. Power is calculated using P = V × I.

Question 3: Describe the mechanism by which electrical energy is converted into heat in a resistor.

Answer: When current flows through a resistor, electrical energy is converted into heat due to resistance, which opposes the flow of electrons and causes energy dissipation as heat.

Question 1: A household appliance operates at a voltage of 120 V and draws a current of 2 A. Calculate its power consumption in watts.

Answer: P = V × I = 120 V × 2 A = 240 W

Question 2: An electric heater has a power rating of 1500 W. If it is connected to a 230 V supply, what is the current flowing through it?

Answer: I = P / V = 1500 W / 230 V ≈ 6.52 A

Question 3: A light bulb uses 60 W of power and is connected across a 230 V power supply. What is the current flowing through the bulb?

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

Question 1: Describe the safety precautions one should take when working with high-power electrical appliances.

Answer: Ensure the appliance is unplugged before servicing, avoid water contact, use insulated tools, and do not overload circuits.

Question 2: Identify the variables that affect the power consumption of an electrical device.

Answer: Voltage, current, and resistance are variables that affect power consumption.

Question 3: Design a simple experiment to measure the power consumption of a household device. Include the variables you would control and safety considerations.

Answer: Set up a voltmeter and ammeter in series with the device to measure voltage and current, then calculate power using P = V × I. Control variables include voltage supply stability and device settings. Safety precautions include ensuring proper insulation, avoiding water contact, and switching off power before connecting or disconnecting measurement devices.

Question 1: A city’s electrical grid supplies power at 230 V. An industrial motor consumes 15 kW of power. Calculate the current drawn by the motor.

Answer: I = P / V = 15,000 W / 230 V ≈ 65.22 A

Question 2: Explain how understanding power equations helps in designing energy-efficient household appliances.

Answer: Knowing power equations allows engineers to optimize appliances to use less energy while maintaining performance, reducing electricity bills and environmental impact.

Question 3: Identify a real-world device where reducing power consumption is critical and explain why.

Answer: LED lighting is a real-world device where reducing power is critical to save energy, reduce heat output, and extend battery life in portable devices.