EXTRA Q AND A OF CHAPTER ...POWER OF ELECTRICITY

EXTRA QUESTION ANSWERS
                                  STD 6 
                   POWER OF ELECTRICITY

Q1: What will happen if we join two terminals of electric cell directly through a wire?
Ans:
If we join two terminals of electric cell directly through a wire, the chemical in an electric cell get used up very fast and the cell will stop working.
Q2: What is an electric circuit?
Ans :Arrangement that provides a complete path for electricity to pass (current to flow) is known as electric circuit.
Q3: Explain how the bulb glows in circuit when it is connected to an electric cell?
Ans:
When the terminals of the bulb are connected with that of electric cell by wires, a current pass through the filament of the bulb and it makes the bulb glow.
Q4: How can an electric bulb get fused?

Ans:
An electric bulb may get fused due to break in its filament. A break in the filament of bulb means break in the path of current between the terminals of electric cell.
Q5. Why is distilled water used in the batteries and not the tap water?
Because distilled water acts as an insulator as it is purest water. Whereas tap water has salts and impurities and acts as a conductor.
Q6.What is the difference between conductor and an insulator? Explain with examples.
ANS. Materials that allow electric current to pass through them are called conductors. For example iron, copper etc. Metals are good conductors. Materials that do not allow electric current to pass through them are called insulators. For example-rubber, plastic etc.
Q7.What is the function of the reflector behind the bulb in headlights of a car?
Ans.
It reflects all the light rays beaming backward and focus it to the front side to provide a powerful beam.

Q8. Why do we use an electric switch? Name some electrical gadgets, which have switches in them.
Ans.
Electric switches are used to supply or cut electricity to the electric appliance by opening or closing the circuit. Some of the gadgets, which have electric switches built into them, are Torch, Mixer grinder.
Q9. Why do electricians use rubber gloves while repairing electrical appliances?
Ans.
Our body is a good conductor of electricity whereas rubber is an insulator. During any repair work, if our body gets in contact with an electric wire carrying current, the current would pass through our body, which would lead to accidents. If we use rubber gloves, it would not allow electricity to pass through us. Therefore, electricians use rubber gloves while repairing electric switch.

Q10. Why do the handles of the tools such as screwdrivers and pliers (used by electricians for repair work) have rubber or plastic wrapped around them? 
Ans.
Plastic and rubber are insulators, which do not allow electricity to pass through them. So, screwdriver and pliers have rubber and plastic covered on them so that electricity may not pass through these tools to the body of the electrician.
 Q11. (A) What is an electric circuit?
(B) Define the types of electric circuit.
Ans.
(A) The diagram that shows the path of electric current is called electric circuit.
(B) There are two types of electric circuit:
(a) Open electric circuit: The circuit in which electrical contact at any point is broken is called open electric circuit.
(b) Closed electric circuit: The circuit in which electric current flows from one terminal of a cell or battery to the other is called a closed circuit.

Q12. Why did the bulb glow in fig2 but not in fig1 ?
 

                            FIG1                                                                        FIG2                                                   
Ans : in fig1 both the terminals of the cell are connected to the same terminal in the bulb. Therefore the circuit is not complete and the bulb does not glow.the two terminals of a cell should always be connected to two different terminals of the bulb then only the bulb glows (as in fig2)

Q13. How a primary cell different from a secondary cell ?
Ans.
Primary cell
Secondary cell
1.Can not be recharged or reused
1.Can  be recharged or reused
2.smaller in size
2. large in size
3.solid electrolyte
3. liquid electrolyte
4. cells donot leak
Cells leak
5.easy to handle
5.difficult to handle
6. more expensive
6. less expensive

                   

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