NCERT Solutions for Class 8 Science Some Natural Phenomena

Select the correct option in questions 1 and 2.

1. Which of the following cannot be charged easily by friction?

(a) A plastic scale

(b) A copper rod

(c) An inflated balloon

(d) A woolen cloth

Ans. (b) A copper rod.

2. When a glass rod is rubbed with a piece of silk cloth the rod

(a) and the cloths both acquire positive charge.

(b) becomes positively charged while the cloth has a negative charge.

(c) and the cloth both acquire negative charge.

(d) becomes negatively charged while the cloth has positive charge.

Ans. (b) becomes positively charged while the cloth has a negative charge.

3. Write T against true and F against false in the following statements.

(a) Like charges attract each other. (T/F)

(b) A charged glass rod attracts a charged plastic straw. (T/F)

(c) Lightening conductor cannot protect a building from lightening. (T/F)

(d) Earthquakes can be predicted in advance. (T/F)

Ans. (a) (F)

(b) (T)

(c) (F)

(d) (F)

4. Sometime, a crackling sound is heard while taking off a sweater during winters. Explain.

Ans. The cracking sound is heard because when the sweater is rubbed while taking it off, it acquires a small charge.

5. Explain why a charged body loses its charge if we touch it with our hand.

Ans. Our body is a conductor of electricity. When we touch a charged body with our hand, the charged body loses charge to the earth through our body.

6. Name the scale on which the destructive energy of earthquake is measured. An earthquake measures 3 on this scale. Would it be recorded by seismograph? Is it likely to cause much damage?

Ans. The destructive energy of an earthquake is measured on a scale called Richter scale.

An earthquake measure 3 on this scale will be recorded by a seismograph. Whoever, it is not likely to cause much damage.

7. Suggest three measures to protect ourselves from lightening.

Ans. (a) Hearing thunder, we should rush to a safer place like hours or building.

 (b) If no proper shelter is available we and in open, never hide under a tree of electric pole.

 (c) The telephone cord, electric wires and metal pipes should be avoided from touching.

NCERT Solutions for Class 8 Science Some Natural Phenomena

8. Explain why a charged balloon is repelled by another charged balloon whereas an uncharged balloon is attracted by another charged balloon?

Ans. A charged balloon is repelled by another charged balloon because both have the same charge and we know that likes charged repel each other.

But charged balloons attract an uncharged balloon and loose its own charge to the other balloon.

9. Describe with the help of a diagram an instrument which can be used to detect a charged body.

Ans. A device that is used to test whether an object is carrying charge or not is known as electroscope.

NCERT Solutions for Class 8 Science Some Natural Phenomena

10. List three states in India where earthquake are more likely to strike.

Ans. The states that fall in seismic zones are Jammu and Kashmir, Himachal Pradesh and Gujarat.

NCERT Solutions for Class 8 Science Some Natural Phenomena

11. Suppose you are outside your home and an earthquake strikes. What precaution would you take to protect yourself?

Ans. Following precautions could be taken to protect ourselves in a earthquake out side the home:

 (a) First find a clear spot, away from building, trees and overhead wires.

 (b) If I am in a car or a bus, I will not come out. Instead I will told driver slowly to clear spot and will not come out till the tremors stop.

12. The weather department has predicted that a thunderstorm is likely to occur on a certain day. Suppose you have to go out on that day. Would you carry an umbrella? Explain.

Ans. No, I would not carry an umbrella, because the pointed rod of the umbrella can become a target of lightening.

NCERT Solutions for Class 8 Science Chapter 15

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