1. All mains cables are covered in plastic layers, This is because plastic is a good ...

  • A. heat conductor
  • B. heat insulator
  • C. electrical conductor
  • D. electrical insulator

2. The safety device that limits the current flow in a plug is the..

  • A. fuse
  • B. cable grip
  • C. earth wire
  • D. insulation

3. Where should the earth wire be connected inside a metal toaster?

  • A. power supply
  • B. heating element
  • C. metal casing
  • D. earth wire not needed in a metal appliance

4. Which of these statements best describes the function of the earth wire in a metal toaster?

  • A. prevents the user getting an electric shock in case the live wire touches the casing
  • B. prevents the user getting an electric shock in case the earth wire touches the casing
  • C. prevents the device from overheating
  • D. protects the device from a short circuit

5-7. This 240 V hair dryer has a case made of plastic. It only needs 2 wires for safe use, and does not need an earth wire.

 

 cloth rubbing plastic

5. Devices like this with an insulating casing are called ...

  • A. earthed
  • B. safety checked
  • C. current controlled
  • D. double insulated

6. The hair dryer has a power rating of 1.2 KW. What current is used when in operation?

  • A. 0.2 A
  • B. 5 A
  • C. 200 A
  • D. 360 A

7. Which of the the following fuses should be used for this hairdryer?

  • A. 1 A fuse
  • B. 3 A fuse
  • C. 5 A fuse
  • D. 13 A fuse

8. Which of the following fuses should be selcted for a 230V, 120 W amplifier?

  • A. 1 A fuse
  • B. 3 A fuse
  • C. 5 A fuse
  • D. 13 A fuse

9+10. The image shows a mains switching safety device found in nearly all homes that has the same function as a fuse. If the current gets too high, the switches automatically turn the circuit off.

 

 static discharge wrist band

9. What is the name of this device?

  • A. mains breaker
  • B. circuit breaker
  • C. mains switcher
  • D. circuit switcher

10. Which of the following best describes the advantage of this device over fuses in mains circuits?

  • A. It does not have exposed live metal parts
  • B. No fuses/parts need replacing if the current gets too high in any circuit
  • C. It is safer as fuses can be unreliable
  • D. It is much cheaper than buying individual fuses