Some Natural Phenomena
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
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.
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)
4. Sometime, a crackling sound is heard while taking off a sweater during winters. Explain.
5. Explain why a charged body loses its charge if we touch it with our hand.
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?
7. Suggest three measures to protect ourselves from lightening.
8. Explain why a charged balloon is repelled by another charged balloon whereas an uncharged balloon is attracted by another charged balloon?
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 earthquake are more likely to strike.
11. Suppose you are outside your home and an earthquake strikes. What precaution would you take to protect yourself?
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.