CAIE IGCSE Physics: Fuses, Breakers & Trip Switches Question Bank
Practise explaining how fuses and trip switches respond to excess current and selecting suitable protection for mains appliances.
- Syllabus
- 2026–2028
- Course
- Physics 0625
Practise explaining how fuses and trip switches respond to excess current and selecting suitable protection for mains appliances.
Fig. 4.1 shows a heater used to warm the air in a room.

Fig. 4.1
The power of the heater is 2.0 kW when it is connected to the mains supply with an e.m.f. of 230 V .
The plug connecting the heater to the mains supply is fitted with a fuse.
Fuse ratings of 3 A,5 A,10 A and 13 A are available.
State which fuse is used. Explain your answer.
fuse
explanation
10 (A) AND
any one from:
- smaller fuse melts in normal use (of the heater) owtte
- smaller fuse stops the heater working (at all)
- larger fuse allows too much current (without melting)
- larger fuse may not melt before the circuit is damaged
- fuse (rating) must be higher than the (normal) current
- the fuse will melt if current goes too high owtte
A2
any one from:
- 10 (A)
- 13 (A) AND fuse (rating) must be higher than (normal) current
- 13 (A) AND 3 A / 5 A fuse melts in normal use owtte
C1