NCERT Solutions for Class 8th Science Chapter 17 Some Natural Phenomenon textual questions and answers based on the latest syllabus of CBSE and JKBOSE
1. Which of the following cannot be charged easily by friction?
Answer: (b) A copper rod
2. When a glass rod is rubbed with a piece of silk cloth the rod
Answer: (d) becomes negatively charged while the cloth has a positive charge.
3. Write T against true and F against false in the following statements:
Answer:
- (a) Like charges attract each other. (F)
- (b) A charged glass rod attracts a charged plastic straw. (T)
- (c) Lightning conductor cannot protect a building from lightning. (F)
- (d) Earthquakes can be predicted in advance. (F)
4. Sometimes, a crackling sound is heard while taking off sweater during winters. Explain.
Answer: The crackling sound is due to the discharge of static electricity that builds up when the sweater is rubbed against the body. This discharge creates a small spark, which produces the sound.
5. Explain why a charged body loses its charge if we touch it with our hand?
Answer: A charged body loses its charge when touched because the charge gets transferred to the ground through the body, which is a conductor. This process is called grounding or earthing.
6. 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?
Answer: The destructive energy of an earthquake is measured on the Richter scale. An earthquake that measures 3 on this scale would be recorded by a seismograph but is unlikely to cause much damage.
7. Suggest three measures to protect ourselves from lightning.
Answer:
- Stay indoors during a thunderstorm.
- Avoid using electrical appliances and phones.
- Do not take shelter under trees or near tall objects.
8. Explain why a charged balloon is repelled by another charged balloon whereas an uncharged balloon is attracted by another charged balloon?
Answer: A charged balloon is repelled by another charged balloon because they have like charges, which repel each other. An uncharged balloon is attracted by a charged balloon because the uncharged balloon gets polarized, creating an induced opposite charge that attracts the charged balloon.
9. Describe with the help of a diagram an instrument which can be used to detect a charged body?
Answer: An electroscope can be used to detect a charged body. It typically consists of a metal rod with thin metal leaves (usually gold or aluminum) at the bottom. When a charged object is brought near the metal rod, the leaves spread apart, indicating the presence of a charge.
10. List three states in India where earthquakes are more likely to strike.
Answer:
- Jammu and Kashmir
- Himachal Pradesh
- Uttarakhand
11. Suppose you are outside your home and an earthquake strikes. What precaution would you take to protect yourself?
Answer:
- Move to an open area away from buildings, trees, and power lines.
- If you are in a vehicle, stop in a clear area and stay inside.
- Drop to the ground, take cover under sturdy furniture, and hold on until the shaking stops.
12. 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.
Answer: It is not advisable to carry an umbrella during a thunderstorm as the metal parts can attract lightning. Instead, it is safer to stay indoors until the thunderstorm passes.
