Electrical Circuits Quiz 1

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

A domestic circuit includes a 30 A fuse. This protects the wiring if there is too much current in the circuit. In which wire is the 30 A fuse positioned, and what does it do when it operates?

• A

• B

• C

• D

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

The diagram shows a 10 Ω resistor and a 20 Ω resistor connected in a potential divider circuit. What is the reading on the voltmeter?

• 4.0 V

• 6.0 V

• 8.0 V

• 12.0 V

In the circuit shown, only one of the fuses has blown, but none of the lamps is lit. Which fuse has blown (meledak)?

• A

• B

• C

• D

In an electrical circuit, what is the purpose of a fuse (sekring)?

• 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

A fuse is used to protect an electric circuit. Which diagram shows where the fuse should be connected?

• A

• B

• C

• D

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?

• Position of fuse: X | Position of circuit-breaker: X

• Position of Fuse: Y | Position of circuit-breaker: X

• Position of fuse: X | Position of circuit-breaker: Y

• Position of fuse: Y | Position of circuit-breaker: Y

An appliance is connected to a mains supply. Its circuit also contains a switch and a fuse. Which circuit shows the fuse in the correct position?

• A

• B

• C

• D

In the circuit shown, the current from the battery divides equally between the two lamps. Each ammeter reads 6.0 A. What is a suitable rating for the fuse in this circuit?

• 3.0 A

• 6.0 A

• 10.0 A

• 13.0 A