NCERT Science Class-VI Chapter-12: Electricity and Circuits Solutions

 

Exercises

Q 1: Fill in the blanks:

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

(b) An electric cell has _______________ terminals.

Ans:

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

(b) An electric cell has two terminals.

 

Q 2: Mark ‘True’ or ‘False’ for 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) Electric current can pass through a sheet of thermo Col.

 Ans:

(a) Electric current can flow through metals. (True)

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

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

 

Q 3: Explain why the bulb would not glow in the arrangement shown in Fig. 12.13.

Ans: The handle of screwdriver is made up of insulator, which does not allow current to flow. Thus, current will not flow in the circuit.

 

Q 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.

Ans:

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

Ans: A electric switch is a device that either breaks the circuit or completes it. When switch is ON, the current will flow and when switch is OFF, the current will not flow in the circuit.  In radio, Television, Iron, Washing Machine Refrigerator, mobiles, torch and electric toys have in-built switches.

 

Q 6: Would the bulb glow after completing the circuit shown in Fig. 12.14 if instead of safety pin we use an eraser?

Ans: Eraser is an insulator which do not allow current to flow through the circuit. Hence circuit will not be completed and bulb will not glow.

 

Q 7: Would the bulb glow in the circuit shown in Fig. 12.15?

Ans: Both the wire are connected to only one terminal of the bulb, so current will not flow through the bulb and it would not glow. We should make a correction as follows:

 

Q 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.

 Ans: Since the object allows current to flow and completes the circuit that makes bulb to glow. Hence object is a conductor.

 

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

Ans: Rubber gloves are insulators which do not allow the current to flow through it. Electricians may accidentally come in contact with live wires (wires carrying current). Since human body is a good conductor, electricians may get shock. To prevent themselves from electric shock , the electricians use rubber gloves while repairing.

 

Q 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?

 Ans: The handles of the tools like screwdrivers and pliers used by electricians for repair work usually have plastic or rubber covers on them as plastic is an insulator which protect the electricians from severe electric shocks and accidents.