Q33. Which of the following cannot be charged easily by
(a) A plastic scale
(b) A copper rod
(c) An inflated balloon
(d) A woollen cloth.
Ans. (b) A copper rod
Q34. What damage is caused by lightning?
When lightning strikes a tree, it can burn up the tree. And when a person is
hit by lightning during a thunderstorm, then electric energy passes through the
body of the person due to which the person get severe burns and get killed.
Thus, it can cause a lot of destruction by damaging property, trees and killing
Q35. When a glass rod is rubbed with a piece of silk cloth the
(a) and the cloth both acquire positive charge.
(b) becomes positively charged while the cloth has a negative
(c) and the cloth both acquire negative charge.
(d) becomes negatively charged while the cloth has a positive
Ans. (b) becomes positively charged while the cloth
has a negative charge.
Q36. What will happen when the metal top of an electroscope is touched
with a glass rod which has been rubbed with silk cloth? Give reason for your
Ans. The aluminium foil strips receive the same charge
from the charged glass rod through the paper clip. The strips carrying similar
charges repel each other and they become wide open.
Q37. What happens when you touch the paper clip of a self-made
Electroscope? Why does it happen? What is this process called?
Every time the foil strips collapse as soon as we touch the paperclip with
hand. The reason is that the foil strips lose charge to the earth through our body.
The process of transferring of charge from a charged object to the earth is
Q38. How can we determine if an object is charged or not?
Ans. An electroscope may be used to detect whether a
body is charged or not. When the object is touched with the metal
cap of an electroscope, both the metal cap and the leaves acquire the same charge
from the charged object through the paper clip. It will cause the leaves to
diverge showing that the object was charged.
Q39. What is lightning conductor? How does it work?
How does a lightning conductor protect a tall building?
Lightning Conductor is a device used to protect buildings from the effect of lightning.
A metallic rod, taller than the building, is installed in the walls of the building
during its construction. One end of the rod is kept out in the air and the other
is buried deep in the ground. The rod provides easy route for the transfer of
electric charge to the ground.
Q40. What are the various effects of an earthquake?
Ans. The various effects of an earthquake are:
They can cause immense damage to buildings,
bridges, dams and people. There can be a great loss to life and property.
The earthquakes can cause floods,
landslides and tsunamis.
A major tsunami occurred in the Indian
Ocean on 26th December 2004. All the coastal areas around the ocean suffered
Q41. What will you do to protect yourself from lightning if you
are in an open field?
Ans. If no shelter is available and we are in an open
field, we should stay far away from all trees. We should stay away from poles
or other metal objects. We should not lie on the ground instead we
should squat low on the ground. We should place our hands on our knees with our
head between the hands. This position will make us the smallest target to be
Q42. Explain why a charged balloon is repelled by another
charged balloon whereas an uncharged balloon is attracted by another charged
Ans. A charged balloon is repelled by another charged
balloon because both the balloons have same type of charges and like charges
repel each other. Whereas an uncharged balloon is attracted by another charged
balloon because charged balloon induces opposite charges in the nearer end of
the uncharged balloon by electric induction and unlike charges attract each