Q18. What are seismic waves?
Q19. Which device is used to protect buildings from the effect of lightning?
Q20. What is an earthquake? What causes them to happen?
Q21. If scientists know so much about earthquakes, can they also predict when and where the next one will strike?
Q22. Other than earthquakes what causes tremors on the earth?
Q23. A positively charged object attracts another charged object placed near it. What is the nature of charge on the other object?
Q24. Explain why a charged body loses its charge if we touch it with our hand.
Q25. What was the magnitude of Bhuj and Kashmir earthquakes on the Richter scale?
Q26. Why does a plastic comb rubbed with dry hair attract tiny pieces of paper?
Q27. Name the scientist who showed that lightning and the spark from your clothes are essentially the same phenomena.
Q28. Why is it not safe to stay under a tree during a thunderstorm?
Q29. When a charged refill is touched with the metal top of an electroscope, its aluminium leaves diverge. Give reason.
Q30. What happens when plates brush past one another, or a plate goes under another due to collision?
Q31. 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.
Q32. Sometime, a crackling sound is heard while taking off sweater during winters. Explain.