Exercise
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 woollen cloth.
Answer:
(b) A copper rod.
2. When a glass rod is rubbed with a piece of silk cloth the rod
(a) and the cloth 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 a positive charge.
Answer:
(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 attract a charged plastic straw (T/F)
(c) Lightning conductor cannot protect a building from lightning (T/F)
(d) Earthquakes can be predicted in advance (T/F)
Answer:
(a)-f (b)-t (c)-f (d)-f
4. Sometime, a crackling sound is heard while taking off sweater during winters. Explain.
Answer:
A crackling sound is heard because when the sweater is rubbed while taking it, off, it acuquires a small charge.
5. Explain why a charged body loses its charge if we touch it with our hand.
Answer:
Our body is a conductor of electricity. When we touch a charged body loses charge to the earth through our body.
6. Name the scale on which the destructive energy of an earthquake is measured. An earthquake measures 3 on this scale. Would it be recorded by a seismograph? Is it likely to cause much damage?
Answer:
The destructive energy of an earthquakq is measured on a scale called Richter scale.
An earthquake that meausure 3 on the Richter scale will be recorded by seismograph However, it is not likely to cause much damage.
7. Suggest three measures to protect ourselves from lightning.
Answer:
(i) We should rush to a safer place like house or building.
(ii)
8. Explain why a charged balloon is repelled by another charged balloon whereas an uncharged balloon is attracted by another charged balloon?
Answer:
A charged ballon is replled by another ballon beecause both have the same charge. And we know similar charges repel each oother.
Butt a charged ballon attracts an uncharged ballon and lose itts own charge too the other ballon.
9. Describe with the help of a diagram an instrument which can be used to detect a charged body.
10. List three states in India where earthquakes are more likely to strike.
Answer:
The states that fall in seismic zones are more earthquake-prone. Jammu and Kashmir, Himachal Pradesh, and Gujrat are a few such states.
