Question 1: Define a fuse and explain its primary purpose in an electrical circuit.

Answer: A fuse is a safety device consisting of a thin wire that melts when excess current flows, thereby protecting the circuit from damage.

Question 2: Describe the mechanism by which a fuse prevents damage to electrical appliances.

Answer: The fuse melts and breaks the circuit when the current exceeds its rated capacity, stopping the flow of excessive current that could damage appliances.

Question 1: A fuse is rated at 13 A and is used in a household circuit. What is the maximum power (in watts) it can safely handle if the supply voltage is 230 V?

Answer: Power = Voltage × Current = 230 V × 13 A = 2990 W

Question 2: Calculate the resistance of a fuse wire that carries a current of 5 A with a voltage across it of 12 V. Use Ohm’s Law (R = V / I).

Answer: Resistance = 12 V / 5 A = 2.4 Ω

Question 1: Outline the steps you would take to safely replace a blown fuse in a household circuit.

Answer: Turn off the power supply, identify the correct fuse rating, remove the blown fuse carefully, insert a new fuse with the same rating, and then switch the power back on while ensuring safety precautions are followed.

Question 2: Identify three safety precautions to observe when working with mains electricity and fuses.

Answer: Turn off the main power before working, use insulated tools, and ensure hands are dry and the work area is safe from water.

Question 1: A household fuse rated at 3 A blows when a new appliance is connected. The appliance operates at 230 V. What could be the reason for the fuse blowing?

Answer: The appliance may be drawing a current higher than 3 A, possibly due to a fault or overload, causing the fuse to blow to protect the circuit.

Question 2: If a fuse wire has a resistance of 0.5 Ω and carries a current of 4 A, what is the voltage across it? (Use V = I × R).

Answer: Voltage = 4 A × 0.5 Ω = 2 V

Question 1: Explain how fuses contribute to electrical safety in domestic wiring systems. Include in your answer the types of faults they protect against, the importance of choosing the correct fuse rating, and what happens when a fuse blows.

Answer: Fuses protect domestic wiring by preventing excessive current flow that could cause overheating, fires, or damage to appliances. They are designed to melt and disconnect the circuit when the current exceeds their rated capacity, thus preventing faults such as short circuits or overloads from causing harm. Choosing the correct fuse rating is crucial; a fuse rated too high may not blow in time to prevent damage, while one rated too low may blow unnecessarily during normal operation. When a fuse blows, it indicates a fault or overload, and the fuse must be replaced with one of the same rating to restore safety.

Question 1: Describe how fuses are used in the automotive industry to protect electrical systems.

Answer: Fuses in vehicles protect electrical circuits by melting when excess current flows, preventing damage to sensitive components like the ECU, lights, and sensors.

Question 2: Explain why modern electronic devices often incorporate resettable circuit breakers instead of traditional fuses.

Answer: Because resettable circuit breakers can be reused after tripping, providing convenience and cost savings, whereas traditional fuses need replacement after blowing.