NCERT Class VIII Science Solutions: Chapter 15-Some Natural Phenomena Part 3

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Question 9:

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

Answer:

Take an empty jam bottle. Take a piece of cardboard slightly bigger in size than the mouth of the bottle. Pierce a hole in it so that a metal paper clip could be inserted. Cut two strips of aluminium foil about 4 cm × 1 cm each. Hang them on the paper clip as shown. Insert the paper clip in the cardboard lid so that it is perpendicular to it. Charge a refill and touch it with the end of the paper clip.

The aluminium foil strips receive the same charge from the charged refill through the paper clip. The strips carrying similar charges repel each other and they become wide open. Such a device can be used to detect whether an object is carrying charge or not. This device is known as electroscope.

Image result for electroscope

Electroscope

Question 10:

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

Answer:

Three states in India are Gujarat, Rajasthan and Himachal Pradesh.

In India, the areas most threatened are Kashmir, Western and Central Himalayas, the whole of North-East, Ran of Kutch, Rajasthan and the Indo – Gang etic Plane. Some areas of South India also fall in the danger zone.

Question 11:

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

Answer:

During the earthquake, I would take the following precaution:

  • I would try to find a clear spot, away from buildings, trees and overhead power lines. Drop to the ground.

  • If I am in a car or a bus, do not come out. Ask the driver to drive slowly to a clear spot. I will not come out till the tremors stop.

Question 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.

Answer:

Carrying umbrella is not a good idea at all during thunderstorms. As during the thunderstorm, the speed of wind will blow away the umbrella

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