NCERT Solutions for Class 6 Science for chapter 12 Electricity and Circuits
1. Fill in the blanks:
- A device that is used to break an electric circuit is called a _____.
- An electric cell has _____
(a) A device that is used to break an electric circuit is called a switch.
Explanation: Switch is a simple device that either breaks the circuit or completes it. It controls the flow of electricity in the circuit.
(b) An electric cell has two terminals.
Explanation: An electric cell has two terminals, a negative terminal and a positive terminal.
2. Mark ‘True’ or ‘False’ for the following statements:
(a) Electric current can flow through metals.
(b) Instead of metal wires, a jute string can be used to make a circuit.
(c) lectric current can pass through a sheet of thermocol.
(a) Electric current can flow through metals. (True)
Explanation: Electric current can pass through metals as they allow an electric current to flow through them easily.
(b) Instead of metal wires, a jute string can be used to make a circuit. (False)
Explanation: Jute string is an insulator. Hence, electric current cannot pass through it.
(c) Electric current can pass through a sheet of thermocol. (False)
Explanation: Thermocol is also an insulator. Hence, electric current cannot pass through it.
3. Explain why the bulb would not glow in the arrangement shown in Fig.12.13.
Answer: In the given circuit, a tester holder is connected in series. Electric current cannot pass through tester holders because it is a bad conductor
of electricity. Hence, the current will not flow through the circuit and hence, the 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
In order to complete the circuit, the positive terminal of the cell should be connected to one end of the bulb, and the other terminal of the bulb should be connected to the other end of the bulb. It can be shown in the above figure.
5. What is the purpose of using an electric switch? Name some electric gadgets that have switched built into them.
Answer: A switch is used to complete or break an electric circuit. If the switch is ‘ON’, then current will flow through the circuit. On the other hand, if the switch is ‘OFF’, then current will not flow through the circuit. Electric fans, electric lamps, washing machines, juicers and mixers, etc. have switches built into them.
6. Would the bulb glow after completing the circuit shown in Fig. 12.14, if we use an eraser instead of a safety pin?
No. The bulb will not glow if we connect an eraser in the circuit. It is because erasers are bad conductor of electricity. They do not conduct electricity. The circuit becomes an open circuit.
7. Would the bulb glow in the circuit shown in Fig. 12.15?
Answer: No. The bulb will not glow because the two terminals of the cell are connected to the single terminal of the bulb. In order to complete the circuit, the two terminals of the battery should be connected to the two terminals of the bulb.
8. Using the ‘conduction tester’ on an object, it was found that the bulb begins to glow. Is the object a conductor or an insulator? Explain.
Answer: The bulb of the conduction tester glows when the tester is touched with the object. It shows that the given object conducts electricity. Hence, the object is a conductor in nature.
9. Why should an electrician use rubber gloves while repairing an electric switch at your home? Explain.
Answer: An electric switch conducts electricity through its internal parts and one may get an electric shock if it is touched with naked hands. Hence, it should be touched with rubber gloves in hand because rubber cannot conduct electricity.
10. Handles of tools such as screwdrivers and pliers used by electricians for repair work usually have plastic or rubber cover on them. Can you explain why?
Answer: Plastics and rubbers are the bad conductor of electricity. Therefore, handle of tools such as screwdrivers, pliers, etc. which are used by electricians to repair electrical appliances usually have plastic or rubber cover on them.