SOME NATURAL PHENOMENA

If the metal clip used in the electroscope is replaced by an ebonite
rod and a charged body is brought in contact with it, will there
be any effect on the aluminium strips? Explain.

What precautions would you take if lightning occurs while you
are outside the house?

Explain why it is safer to use a wireless telephone instead of a
landline telephone during lightning.

Mention three precautions that you will take to protect yourself
if earthquake strikes when you are inside the house.

Explain how lightning takes place?

The strips of an electroscope diverge when a charged body is
brought in contact with the metal clip. Now the clip is touched
gently by our hand. What will happen to the strips? Explain.

In an electroscope if a negatively charged body is brought in
contact with the metal clip, the strips of the electroscope diverge.
If now another charged object carrying equal amount of prositive
charge is brought in contact with the clip, what will happen?

Explain how does lightning conductor protects a building from
getting struck by lightning.

You might have observed on a dry day that when you touch the
screen of a television or computer monitor (with picture tube),
you get a slight shock. Why does it happen?

If the materials used for constructing a building were good
conductors, do you think lightning will strike the building. Will
the lightning conductor be still required to be installed in the
building?

If air and cloud were good conductors of electricity, do you think
lightning could occur? Explain.

During the construction of a building the lightning conductor
was left hanging in the air by mistake. Would the lightning
conductor be still effective? Explain.

Plastic straws A and B are rubbed with dry cotton cloth. What
will happen if they are brought near each other?

If a charged plastic straw is brought near another uncharged
plastic straw, what will happen?

Is it possible to predict the occurrence of an earthquake?

State whether the following are True or False.
(a) Earthquakes occur all the time all over the world.
(b) The plates of the outermost layer of the earth are always in
continuous motion.
(c) Tremors on the earth can also be caused by the eruption of a
volcano.
(d) The process of electric discharge cannot occur between clouds
and the earth.
(e) Bathing outdoors should be avoided during thunderstorm.

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.

Suppose you are outside your home and an earthquake strikes. What precaution would you take to protect yourself?

List three states in India where earthquakes are more likely to strike.

Describe with the help of a diagram an instrument which can be used to detect a charged body.

Explain why a charged balloon is repelled by another charged balloon whereas an uncharged balloon is attracted by another charged balloon?

Suggest three measures to protect ourselves from lightning.

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?

Explain why a charged body loses its charge if we touch it with our hand.

Sometimes, a crackling sound is heard while taking off a sweater during winters. Explain.

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) Lightning conductor cannot protect a building from lightning. (T/F)

(d) Earthquakes can be predicted in advance. (T / F)

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.

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