CIE iGCSE Co-Ordinated Science P4.4 Electrical safety Exam Style Questions Paper 1
▶️ Answer/Explanation
A fuse should have a rating slightly higher than the normal operating current, but not too high that it doesn’t protect the circuit.
The heater draws 3.0 A, so a 5 A fuse is most suitable. A 1 A or 2 A fuse would blow even under normal operation, and 240 A is too high to provide protection.
✅ Answer: (C)
The heater draws 3.0 A, so a 5 A fuse is most suitable. A 1 A or 2 A fuse would blow even under normal operation, and 240 A is too high to provide protection.
✅ Answer: (C)
▶️ Answer/Explanation
A fuse is a safety device that protects a circuit by melting and breaking the circuit if the current exceeds a safe value. A fixed resistor limits current, a switch controls the circuit on/off, and a variable resistor changes resistance – none of these primarily function as a protective component.
✅ Answer: (B)
✅ Answer: (B)
▶️ Answer/Explanation
A fuse must have a rating just above the normal operating current so it does not blow during ordinary use.
The 1 A and 5 A fuses are both below 6.0 A, so they would blow even under normal conditions.
The 20 A fuse is far too high and would allow a dangerous fault current to flow without breaking the circuit.
The 8 A fuse sits just above the 6.0 A normal current, allowing safe operation while still protecting against a fault.
✅ Answer: (C)
The 1 A and 5 A fuses are both below 6.0 A, so they would blow even under normal conditions.
The 20 A fuse is far too high and would allow a dangerous fault current to flow without breaking the circuit.
The 8 A fuse sits just above the 6.0 A normal current, allowing safe operation while still protecting against a fault.
✅ Answer: (C)
▶️ Answer/Explanation
To gradually increase the current, the circuit needs a variable resistor in series with the fuse to control current smoothly.
An ammeter in series with the fuse is also needed to read off the exact current at the moment the fuse blows.
Only one diagram includes both the fuse, a variable resistor and an ammeter correctly connected in series in a complete circuit.
✅ Answer: (D)
An ammeter in series with the fuse is also needed to read off the exact current at the moment the fuse blows.
Only one diagram includes both the fuse, a variable resistor and an ammeter correctly connected in series in a complete circuit.
✅ Answer: (D)
▶️ Answer/Explanation
A fuse must have a current rating that is higher than the normal operating current of the appliance, so it does not blow during normal use.
The kettle operates at 9.0 A, so fuses rated at 1 A, 3 A or 8 A would all be too low and would melt during normal operation.
The 13 A fuse is the smallest standard rating above 9.0 A, making it the most appropriate choice.
✅ Answer: (D)
The kettle operates at 9.0 A, so fuses rated at 1 A, 3 A or 8 A would all be too low and would melt during normal operation.
The 13 A fuse is the smallest standard rating above 9.0 A, making it the most appropriate choice.
✅ Answer: (D)