Electrical Principles – Practice Questions (Unit 202)

What is the function of a residual current device (RCD)?

• Reduce the electricity bill

• Detect earth faults and disconnect the supply

• Limit the voltage in a circuit

• Regulate current in an AC system

Which of the following materials is a good electrical conductor?

• Rubber

• Glass

• Copper

• Plastic

What is the unit of electrical resistance?

• Watt

• Volt

• Amp

• Ohm

Before starting work on an electrical circuit, you must always:

• Turn off the central heating

• Inform the customer

• Lock off and isolate the circuit

• Use a test lamp

The main purpose of earthing in an electrical installation is to:

• Prevent overload

• Increase voltage

• Protect against electric shock

• Balance the circuit load

Which of the following is used to measure current in a circuit?

• Voltmeter

• Ammeter

• Ohmmeter

• Wattmeter

The colour used for the protective earth conductor is:

• Blue
• Green and yellow

• Brown

• Black

The most common cause of electric shock is:

• High resistance

• Short circuit

• Good insulation

• Strong fuse

Which type of current alternates direction periodically?

• AC

• DC

• Static current

• Continuous voltage

Which of the following components is designed to protect a circuit from overload?

• Transformer

• MCB (Miniature Circuit Breaker)

• RCD (Residual Current Device)

• Contactor