Case Study Based Questions: Some Natural Phenomena | Science Class 8 PDF Download

Case Study 1

Roy and his friends were swimming in a pool. Suddenly he saw a huge flash of light in the sky and heard a loud sound of thunder. His friends continued swimming but Roy asked everyone to stop swimming and be safe. Few of his friends immediately got into the car. Roy and a few of them went inside the nearby building.

Q1: What should Roy and his friends do to save themselves from a thunderstorm?
(a) They should stop swimming and stand in the pool.
(b) They should stop swimming and go inside a building.
(c) They should continue swimming.
(d) They should run immediately and take shelter under a tall tree.
Ans: (b)
Sol: During a thunderstorm, it is safest to get out of the water and seek shelter inside a building to avoid lightning strikes and electrical hazards.

Q2: What should be done by Roy’s friends who got into the car?
(a) They should stay inside the car with doors and windows closed.
(b) They should stay inside the car with doors and windows open.
(c) They should stay inside the car with doors closed but windows opened.
(d) They should stay inside the car with doors opened but windows closed.
Ans: (a)
Sol: Staying inside a car with doors and windows closed provides a safe environment during a thunderstorm because the car’s metal body acts as a Faraday cage, protecting occupants from lightning.

Q3: Identify the correct statement/statements related to lightning and thunderstorm.
i. Lightning is an electric discharge that occurs in nature on a large scale.
ii. Lightning Conductor is a device used to protect buildings from the effect of lightning.
iii. It is safe to travel on a motorbike during a thunderstorm.
(a) Both i and ii
(b) Both ii and iii
(c) Only i
(d) Only iii
Ans: (a)
Sol: Lightning is indeed an electric discharge and a lightning conductor is used to protect buildings. However, it is not safe to travel on a motorbike during a thunderstorm due to the risk of being struck by lightning.

Case Study 2

Seetha prepared an electroscope as shown in the figure. She has replaced the copper wire with ebonite rod. When charged body was bought in contact with the ebonite rod, she observed that the aluminium strips did not diverge.
Q: What is the reason behind it?

Ans: The aluminium strips did not diverge because the ebonite rod is an insulator and does not conduct electricity. In an electroscope, the metal wire or rod (usually made of a conductor like copper) is essential for conducting the charge from the charged body to the aluminium strips. Since the ebonite rod is a non-conductor, it prevents the flow of charge to the aluminium strips, which is why they did not diverge. For the electroscope to function properly and show divergence of the strips, a conductive material must be used to transfer the charge.