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

Answer: A fuse is a safety device consisting of a metal wire or strip that melts when excessive current flows through it, thereby disconnecting the circuit to prevent damage or fire. Its primary function is to protect electrical devices and prevent electrical fires caused by overloads or short circuits.

Question 2: Describe how a fuse works when an overload occurs in a circuit.

Answer: When an overload occurs, the current exceeds the fuse's rated current, causing the metal filament to heat up and melt. This breaks the circuit, stopping the flow of current and preventing damage or fire.

Question 3: Multiple Choice: Which of the following best describes the purpose of a fuse in household wiring?

Answer: To prevent overloads and short circuits

Question 4: Fill in the blank: A fuse rated at 13 A means it is designed to melt if the current exceeds __________ amperes.

Answer: 13

Question 5: Explain the importance of using the correct fuse rating for an appliance.

Answer: Using the correct fuse rating ensures that the fuse will blow only in the event of a genuine overload or fault, protecting the appliance without causing unnecessary disconnection. Using a fuse with a rating that is too high may fail to protect the device, risking damage or fire. Conversely, a fuse with a rating too low may blow during normal operation, causing inconvenience and unnecessary replacements.

Question 6: Calculate the fuse rating required for a circuit that normally carries a current of 5 A but can handle up to 7 A in case of short-term surges. State your reasoning.

Answer: A fuse rated at slightly above 5 A but below 7 A would be appropriate, for example, 6 A. This allows normal operation at 5 A, while protecting against surges up to 7 A. The fuse should be rated just above the typical current but below the maximum withstand current to ensure safety.

Question 7: Describe a safety precaution that should be observed when replacing a fuse in a mains electrical device.

Answer: Always switch off the mains supply and unplug the device before replacing the fuse to prevent electric shock. Use a fuse with the correct rating and ensure the replacement is securely fitted.

Question 8: Data Analysis Scenario: A household fuse rated at 13 A blows frequently when the washing machine is running. List possible reasons and suggest solutions.

Answer: Possible reasons include overload due to other appliances on the same circuit, a fault in the washing machine causing it to draw excessive current, or a fuse of incorrect rating. Solutions may involve redistributing appliances across different circuits, inspecting and repairing the washing machine, or replacing the fuse with an appropriate rating if the current one is unsuitable.

Question 9: Explain how fuses contribute to electrical safety in domestic wiring systems.

Answer: Fuses contribute to electrical safety by acting as a protective device that disconnects the circuit when excessive current flows, preventing overheating, damage to appliances, and reducing the risk of electrical fires. They are designed to melt at a specific current, providing a fail-safe mechanism that safeguards both property and lives. Proper selection and maintenance of fuses are essential for ensuring reliable protection in domestic wiring systems.

Question 10: In industries where high currents are involved, explain why specialised fuses are used instead of standard household fuses.

Answer: Specialised fuses are used in industries because they are designed to handle higher currents and voltages safely, have precise breaking capacities, and are often made of materials suitable for extreme conditions. They provide reliable protection and reduce the risk of failure that could lead to equipment damage or safety hazards.