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- 1. Multiple Choice
What is the function of a relay?
to allow a current in one circuit to operate a switch in another circuit
to prevent an electric shock by earthing a metal case
to protect a circuit by melting if the current becomes too large
to transform a d.c. voltage to a different value
- 2. Multiple Choice
After some building work in a house, a bare (uninsulated) live wire is left protruding from a wall. What is the greatest hazard?
a fire
a fuse blows
an electric shock
no current flows
- 3. Multiple Choice
The diagram shows a 10Ω resistor and a 20Ω resistor connected in a potential divider circuit.
4.0V
6.0V
8.0V
12.0V
- 4. Multiple Choice
In the circuit shown, only one of the fuses has blown, but none of the lamps is lit. Which fuse has blown?
A
B
C
D
- 5. Multiple Choice
In an electrical circuit, what is the purpose of a fuse?
to connect the metal case of an appliance to the earth
to cut off the electrical supply if the current is too large
to keep an electrical appliance dry in damp conditions
to maintain a steady voltage as the current varies
- 6. Multiple Choice
The current in a kettle is 10A and it is protected by a 13A fuse. The owner of the kettle replaces the 13A fuse with a 3A fuse.
The fuse blows and the kettle is damaged.
The fuse blows and the kettle is undamaged
The fuse does not blow and the kettle works correctly.
The fuse does not blow but the kettle fails to work
- 7. Multiple Choice
A desk lamp should have a 3A fuse fitted, but a 13A fuse has been fitted by mistake. The lamp is not faulty.
The fuse blows.
The fuse does not blow but the lamp does not light
The lamp draws too much current and the supply cables could melt.
The lamp works normally.
- 8. Multiple Choice
A domestic circuit includes a 30A fuse. This protects the wiring if there is too much current in the circuit. In which wire is the 30A fuse positioned, and what does it do when it operates?
A
B
C
D
- 9. Multiple Choice
In the circuit shown, the current from the battery divides equally between the two lamps. Each ammeter reads 6.0A.
3.0A
6.0A
10.0A
13.0A
- 10. Multiple Choice
6 Each branch of a domestic circuit often includes a circuit-breaker. This protects the wiring if too much current flows in the circuit. In which wire is the circuit-breaker placed and what does it do when it operates?
A
B
C
D
- 11. Multiple Choice
In this circuit, a component at X automatically protects the wiring from overheating if there is a fault.
a circuit-breaker, a fuse or a switch
only a circuit-breaker or a fuse
only a circuit-breaker or a switch
only a fuse
- 12. Multiple Choice
Device that disconnects supply automatically if current exceeds normal value is known as :
Circuit breaker
Fuse
Cable
Capacitor
- 13. Multiple Choice
The device X in this circuit is designed to cut off the electricity supply automatically if too much current flows.
a fuse
a relay
a resistor
an ammeter
- 14. Multiple Choice
Which circuit could be used to determine the resistance of the resistor R?
A
B
C
D
- 15. Multiple Choice
The circuit shows a battery and four lamps. All the lamps are lit. One lamp fails and all the lamps go out. Which lamp failed?
A
B
C
D
- 16. Multiple Choice
The circuit diagram shows a 4.0 Ω resistor and an 8.0 Ω resistor connected to a 6.0 V battery.
0.50A
0.75A
1.5A
2.0A
- 17. Multiple Choice
Either a fuse or a circuit-breaker can be used to protect electrical cables from large currents that
could cause overheating.When a fuse is used, where should it be connected, and when a circuit-breaker is used, where
should it be connected?
A
B
C
D
- 18. Multiple Choice
The diagram shows the connections to an electric heater. Three fuses have been added to the
circuit.
fuse 1, fuse 2 and fuse 3
fuse 1 and fuse 2 only
fuse 1 only
fuse 2 only
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