NCERT Solutions for Class 6 Science Chapter 12 Electricity and Circuits

1. Fill in the blanks :

(a) A device that is used to break an electric circuit is called _______________.

Answer: switch

(b) An electric cell has _______________ terminals.

Answer: two [ a positive and a negative terminal. ]

2. Mark ‘True’ or ‘False’ for following statements:

(a) Electric current can flow through metals.

Answer: True.

(b) Instead of metal wires, a jute string can be used to make a circuit.

Answer: False. [ Materials that does not allow electric current to pass through them are called insulators. Jute string is an insulator. Hence, Jute string can not be used to make circuit. ]

(c) Electric current can pass through a sheet of thermo Col.

Answer: False. [ Materials that does not allow electric current to pass through them are called insulators. ThermoCol is a bad conductor or an insulator. Hence, electric current can not pass through a sheet of thermocol. ]

3. Explain why the bulb would not glow in the arrangement shown in Fig.12.13 (refer diagram from CBSE textbook)

Answer:In a given circuit tester is connected with battery and bulb. One end of the tester is metal and other end is of plastic or rubber. Plastic or rubber are bad conductors of electricity and therefore opposes flow of current through it. Thus, bulb will not glow.

4.Complete the drawing shown in Fig 12.14 to indicate where the free ends of the two wires should be joined to make the bulb glow. Refer fig from CBSE textbook.

Answer: Given circuit is incomplete as it is not connected. To make the bulb glow, one end of switch should be connected to battery and other end to the bulb. This will allow current to flow in the circuit and bulb will glow.

5. What is the purpose of using an electric switch? Name some electrical gadgets that have switches built into them.

Answer: An electric switch is used to break or complete an electric circuit. Also, it is responsible for controlling the flow of electric current. If switch is turned ‘ON’, electric circuit gets complete and current flows through the circuit. If switch is turned ‘OFF’, electric circuit breaks and flow of current stops within the circuit. Some electrical gadgets having inbuilt switches are electrical trimmers, television, grinders, washing machines, wireless computer mouse, etc.

6. Would the bulb glow after completing the circuit shown in Fig. if instead of safety pin we use an eraser?

Answer: No, the bulb will not glow, if eraser is use instead of safety pin. This is because, eraser is an insulator which prevents the flow of current through it.

7. Would the bulb glow in the circuit shown in Fig.

Answer: No. Because the two ends of the battery are connected to the single end of the bulb.

8. Using the “conduction tester” on an object it was found that the bulb begins to glow. Is that object a conductor or an insulator? Explain.

Answer: Electric current passes through the materials that are good conductors of electricity. By using conduction tester, it is found that bulb glows, which suggest that current is passing through the circuit. Hence, object must be a good conductor of electricity.

9. Why should an electrician use rubber gloves while repairing an electric switch at your home? Explain.

Answer: Rubber gloves are made of rubber, which is an insulator. Thus, it prevents flow of current through it and protects from electric shock. Therefore, it is necessary for electricians to use rubber gloves while repairing an electric switch at your home.

10. The handles of the tools like screwdrivers and pliers used by electricians for repair work usually have plastic or rubber covers on them. Can you explain why?

Answer: Plastic and rubber are bad conductors of electricity which resist the flow of current through them. This protects electricians from getting electric shock. Therefore, to prevent from electric shock, handles of tools like screwdrivers and pliers used by electricians for repair work have plastic or rubber covers.

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Download free NCERT textbook class 6 Science – Chapter 12 Electricity and Circuits