Question 1: What is the primary function of a fuse in an electrical circuit?

Answer: To protect the circuit by breaking the flow of current when it exceeds a certain limit, preventing damage or fire.

Question 2: Explain how a fuse prevents overheating and potential fires in household wiring.

Answer: A fuse melts and breaks the circuit when the current is too high, stopping excessive current flow that can cause overheating and fires.

Question 1: A fuse rated for 10 Amps is used in a household circuit. If the current flowing through the circuit suddenly increases to 15 Amps, what will happen to the fuse? Explain why.

Answer: The fuse will melt and break the circuit because the current exceeds its 10 Amp rating, preventing damage or fire.

Question 2: A fuse has a rated current of 7 Amps. The actual current in the circuit is measured as 5 Amps during normal operation. What is the safety margin of this fuse, and is it appropriate for this circuit? Show your calculations.

Answer: Safety margin = (Fuse rating - Actual current) / Actual current = (7A - 5A) / 5A = 0.4 or 40%. Since the fuse's rating is above the normal current, it is appropriate, providing a safety margin.

Question 1: Describe the steps and safety precautions you should follow when replacing a blown fuse in a household circuit.

Answer: First, turn off the main power supply to ensure safety. Use insulated tools to remove the old fuse. Check the fuse rating and replace it with a fuse of the same rating. Ensure the fuse is properly seated before turning the power back on. Always wear protective gloves and avoid touching live parts.

Question 1: In a series of tests, a 5A fuse blows when a lamp is connected, but a 10A fuse does not. The lamp's rated current is 4A. Explain the reason for this observation.

Answer: The 5A fuse is too close to the lamp's current, so it blows to protect the circuit. The 10A fuse can handle higher current without blowing, which is safe for the lamp's 4A current.

Question 2: A household circuit has a fuse rated at 15 Amps. During peak usage, the current reaches 12 Amps. If the appliances connected draw a total of 14 Amps, what does this suggest about the fuse's safety margin and circuit protection?

Answer: Since 14A is below the 15A fuse rating, the fuse will not blow, indicating the circuit is protected under normal operation. The safety margin is 1A (15A - 14A), which is adequate for typical fluctuations.

Question 1: Explain how fuses are important in electrical appliances like microwave ovens and why selecting the correct fuse rating is critical.

Answer: Fuses prevent damage and fire hazards in appliances by breaking the circuit when excess current flows. Using the correct fuse rating ensures protection without unnecessary interruptions.

Question 2: Discuss the advantages and disadvantages of using circuit breakers instead of fuses in modern electrical systems.

Answer: Advantages of circuit breakers include being reusable, faster reset after tripping, and more precise control. Disadvantages include higher cost and complexity. Fuses are simpler, cheaper, but need replacement after blowing, which can be less convenient.