2Exp - Electricity Quiz (Effects and Household)

What is a circuit breaker?

• A type of light switch.

• A switch used in an electrical appliance that uses large current.

• Used to turn on or off the electrical supply to the whole house.

• Used to switch off the electrical supply to one part of the circuit when current in that part of the circuit is too large.

Which statement about circuit breaker is not true?

• It protects the user from being electrocuted.

• it is a switch which will ‘trip’ when there is excess current flowing through.

• it creates short circuit.

• it cuts off electrical supply when the electrical appliance is damaged.

Which of the following is not an electrical hazard?

• Overload sockets

• A faulty socket

• A frayed wire

• A two-pin plug

Which is a result of overloading of electrical appliances?

• high performance of equipment

• inadequate current supply

• overheating of wires and fire may occur

• none of the above

Which is incorrect about fuses?

• A blown fuse should be replaced with one of higher rating so that the appliance can work safely.

• An appliance will work when a metal wire is used to replace the fuse.

• Fuses with different ratings allow different current sizes to flow through them.

• The wire in the fuse melts when too large a current passes through it.

The diagram below show the three wires of an electrical mains supply connected to an electric heater. A current of 4A is flowing from the supply through the “live” wire.

Which pair shows the correct corresponding currents of X and Y in the “neutral” and “earth” wires when the heater is working normally.

• 4A, 0A

• 4A, 4A

• 2A, 2A

• 0A, 4A

Which of the following are safety features to help prevent electric shocks?

I earth wire

II insulated wire

III double insulation in two-pin plug

• I only

• I and III only

• II and III only

• all of the above

The metal casing of a household electric heater is earthed via the main plug. Why is earthing considered necessary?

• To complete the electric circuit

• To prevent the casing from getting too hot to touch

• To protect the casing against a short circuit when user is in contact with the casing

• To reduce the risk of electric shocks when the user is in contact with the metal casing.

Using a frayed wire is dangerous because there will be a risk go getting __?

Using a hairdryer in the bathroom is dangerous because __ can conduct electricity to the user when touching it.