A. Tick (œ“) the correct option:
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
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
3. The two objects rubbed against each other:
(a) will lose electrons
(b) will gain electrons
(c) one will lose and other will gain electrons
(d) none of these
4. Which of the following can be charged with static electricity?
(a) Metal
(b) Alloy
(c) Insulator
(d) Semiconductor
5. Which of the following occurs during lightning?
(a) Nitrogen fixation
(b) Acid rain
(c) Greenhouse effect
(d) None of these
B. State True or False:
1. Like charges attract each other. ……………..
2. A charged glass rod attract a charged plastic straw. ………………..
3. Lightning conductor cannot protect a building from lightning. ……………….
4. Earthquakes can be predicted in advance. ……………..
C. Answer the following questions in short:
1. Sometimes, a crackling sound is heard while taking off a sweater during winters. Explain.
2. Explain why a charged body loses its charge if we touch it with our hand.
3. 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?
4. Suggest three measures to protect ourselves from lightning.
5. Explain why a charged balloon is repelled by another charged balloon whereas an uncharged balloon is attracted by another charged balloon.
6. Describe with the help of a diagram an instrument which can be used to detect a charged body.
7. List three states in India where earthquakes are more likely to strike.
8. Suppose you are outside your home and an earthquake strikes. What precaution would you take to protect yourself?
9. 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.
10. Mention three precautions that you will take to protect yourself if earthquake strikes when you are inside the house.
11. Explain why it is safer to use a wireless telephone instead of a landline telephone?
D. Fill in the blanks:
1. Like charges ……………….. and unlike charges ………………. .
2. The explosive sound heard during lightning is called ……………. .
3. A negatively-charged object will ……………….. a positively charged object.
4. Charging a body by touching it with a charged body is called charging by ……………….. .
E. Match the following:
| ‘A’ | ‘B’ |
| 1. A device which is used to test whether an object is carrying charge or not is known as | a. Earthing |
| 2. The process of transferring of charge from a charged object to the earth is called | b. Electroscope |
| 3. A device used to protect buildings from the effect of lightning is called | c. Earthquake |
| 4. A sudden shaking or trembling of the earth which lasts for a very short time is called | d. Lightning conductors |
F. Open a water tap. Adjust the flow so that it forms a thin stream. Charge a refill. Bring it near the water stream. Observe what happens. Write a short report on the activity:
G. Collect the objects and the materials listed in table. Try to charge each by rubbing with the materials mentioned in the table. Record your findings. You can add more items to table:
