Friday, January 28, 2011

Some sample questions from Physics for SA 2 of CCE class X

  1. List the three phenomenon responsible for the formation of rainbow. (Ans: Refraction, Dispersion, (Total)Internal reflection)

  2. Why do stars twinkle, but planets do not? (Ans: The twinkling is caused by the variation of intensity of light entering our eye from the stars. The starts are far away from us and they are seen in a position different from their actual position caused by atmospheric refraction. The position goes on shifting slightly due to changes in atmospheric conditions, changing the intensity of light received by the eyes. But the planets are relatively closer to us and further they do not emit their own light. The apparent changes in position due to atmospheric refraction is also not considerable. So, planets do not twinkle)

  3. What is meant by power of accommodation of human eye? (The ability of human eye to focus on near by objects as well as far off objects without any time lag is called accomodation and the maximum change in the power of human eye during this process is called power of accomodation; and is equal to 4D)

More questions will be posted soon


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