REVISION QUESTION FOR CLASS 8

SOME NATURAL PHENOMENA

CLASS-8

1. Which of the following cannot be charged easily by friction?
(a) A plasticscscale	(b) A copper rod	(c) An inflated balloon	(d) A woollen cloth.

(a) negative charge (b) positive charge (c ) both positive and negative charge				(d) becomes neutral
4. An electroscope is a device used to:
(a) detect and test small electric charges			(c ) test the presence of magnetic filed
(b) calculate the amount of electrical charge flowing through the conductor (d) none of these
5. Lighting conductors are made of:
(a) plastic	(b) copper	(c ) wood	(d) bakelite

(1)…………….. is a form of static electricity.

(2)When lightning heats the air and causes it to expand rapidly,……………. Is produced.

(3)A charged body attracts an ……………… body.

(4)…………… between two bodies is definite proof that of them are charged

Question and answer.1.What are the two types of charges ?2.Name the material used to transfer of charges from one body to other.3.Name the device which is used to test whether an object is charged or not.4.Define lightning conductor.1.Sometime, a crackling sound is heard while taking off sweater during winters. Explain.2.Explain why a charged body loses its charge if we touch it with our hand.3.Explain why a charged balloon is repelled by another charged balloon whereas an uncharged balloon is attracted by another charged balloon?4.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.5.Why does a charged body attract an uncharged body?1.How many different types of charges are there ? Write the nature of charges on glass rod and silk cloth when they are rubbed each other ?2.What are the causes of sparkling ?3.What is electric discharge ? How does it occur ?4.How does electric discharge occur in clouds ?5.What is static electricity ? How is it differ from electric current ?1.Suggest some measures to protect ourselves from lightning.2.Describe with the help of a diagram an instrument which can be used to detect a charged body.3.Draw and explain the function of Electroscope?4.Write Do’s and Dont’s during thunderstorm.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.When a glass rod is rubbed with a silk cloth, it acquires a6. When a woollen cloth removed in the dark. We see sparks and hear a cracking sound. This is due to: