Friday, 3 June 2011

Electricity and Circuits : NCERT Class VI Science Lesson 12

NCERT Class VI Science textbook:
Lesson 12: Electricity and Circuits.


Exercise

1.Question.Fill in the blanks:
Answer. (a) A device that is used to break and electrics circuit is called *switch.*
        (b) An electric cell has *two* terminals.



2.Question.Mark 'True' or 'False' for the following statements.

Answer.(a) Electric  Circuit can flow through metals. (True)
       (b) Instead of metal wires,a jute sting can be use  to make a circuit. (False)
       (c) Electric current can pass through a sheet of thermacol. (False)

3. Question. Explain why the bulb would not glow in the arrangement show in fig.
Answer. The bulb will not glow because the circuit is disconnected due to presence of an insulator in between.
  

 4.Question. Complete the drawing show in fig. to indicate where the  free ends of the two wires should be joined to make the bulb glow.
Answer.






5.Question. what is he purpose of using an electric switches? Name some electric gadgets that have switches built into them.
Answer. switch is a simple device tht is used to either break the electric circuit or to complete it.
Electric gadgets that have switches built into them are microwaves, freezes,rice cooker, automatic, electric irons,toastr, patty makers.


6.Question. Would the bulb glow after completing the circuit shown in fig. in Q4 if instead of safety pin we use an eraser?
Answer. 'No'.

7. Question. Would the bulb gloe in the circuit. show in fig.

Answer.No.


8. Question.Using the ''conduction tester'' an object it was found that the bulb begins to glow. Is that object a conductor or an insulator? Explain.
Answer.That object is a conductor because electricity can pass through only a conductor  and not through an insulator. Unless the object is conductor, the bulb could not glow.


9.Question. Why should an electrician use rubber gloves while rearing an electric switch at your home?
Answer. The rubber gloves are insulators. This saves electrician from getting shock. That is why an  electrician uses gloves,  while rearing an electric switch.

10.Question. The handles of tools like screwdrivers and pliers used by electrician for repair work usually have plastic or rubber covers on them. Can you explain why?
Answer.Plastic and rubber, both are bad conductor of electricity. Hence, they protect against electric shock. 

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