Detailed Study:

Brief Revision - Important Question Solving

Color Coding of Wires


Frequently Tested Topics:

Important Past Questions:

  • Identify the following wires used in a household circuit:

i) The wire is also called phase wire.

ii) The wire is connected to the top terminal of a three pin socket.


  • State the characteristics required in a material to be used as an effective fuse wire. 

(2012, 2016, 2019)

  • For a fuse, higher the current rating ________ is the fuse wire.


  • Name the device used to protect the electric circuits from overloading and short circuits. On what effect of electricity does the above device work? 


  • What is the colour code for the insulation on the earth wire?


  • Which part of an electrical appliance is earthed?


  • Give two characteristics of copper wire which make it unsuitable for use as fuse wire.


  • Name the material which is used as a fuse wire.


  • Draw a labelled diagram of the staircase wiring for a dual control switch showing a bulb in the circuit.


  • The electrical gadgets used in a house such as bulbs, fans, heater, etc. are always connected in parallel, NOT in series. Give two reasons for connecting them in parallel.​

(2008, 2019)

  • Of the three connecting wires in a household circuit:

i) Which two of the three wires are at the same potential?

ii) In which of the three wires should the switch be connected?

(2007, 2015)

  • Draw a labelled diagram of a three-pin socket.


  • Which wire in a power circuit is connected to the metallic body of the appliance?

(2017, 2019)

  • Name two safety devices which are connected to the live wire of a household electric circuit. Give one important function of each.

(2011, 2018)

  • Name the colour code of the wire which is connected to the metallic body of an appliance.


  • Draw the diagram of a dual control switch when the appliance is switched 'ON".


  • To which wire should the fuse be connected? 


  • Name the transformer used in the power transmitting station of a power plant.


  • What type of current is transmitted from the power station?


  • At what voltage is this current available to our household?

(2012, 2016)

  • Name the device used to increase the voltage at a generating station.


  • At what frequency is A.C supplied to residential houses?


  • Two sets A and B, of three bulbs each, are glowing in two separate rooms. When one of the bulbs in set A is fused, the other two bulbs also cease to glow. But in set B, when one bulb fuses, the other two bulbs continue to glow. Explain why this phenomenon occurs.

Why do we prefer arrangements of Set B for house circuiting? 


  • i) An electrical gadget can give an electric shock to its user under certain circumstances. Mention any two of these circumstances.

ii) What preventive measure provided in a gadget can protect a person from an electric shock? 


  • What is the purpose of using a fuse in an electrical circuit?

(2012, 2018)

  • How should the electric lamps in a building be connected?


  • What is meant by earthing of an electrical appliance? Why is it essential?


  • What will be the effect on the working of an electric bell if instead of a direct current, an alternating current is used?


  • Explain the meaning of the statement 'current rating of a fuse is 5A.'


  • In the transmission of power the voltage of power generated at the generating stations is stepped up from 11kV to 132kV before it is transmitted. Why?


  • In what unit does the domestic electric meter measure the electrical energy consumed? State the value of this unit in S.I unit.​


  • Why should switches always be connected to the live wire?


  • Give one precaution that should be taken while handling switches.




The diagrams (a) and (b) given below are of a plug and a socket with arrows marked as 1, 2, 3 and 4, 5, 6 respectively on them. Identify and write Live (L), Neutral (N), and Earth (E) against the correct number.