UPSC Prelims 1999 · General Studies
Question 116: Science and Technology
Consider the following statements: I. If a person looks at a coin which is in a bucket of water, the coin will appear to be closer than it really is. II. If a person under water looks at a coin above the water surface, the coin will appear to be at a higher level than it really is. Which of the above statements is/are correct?
AnswerThe answer is (a).
Refraction makes an object under water look raised: light bends away from the normal as it leaves the water, so the coin in the bucket seems nearer the surface and closer to the eye (I). A diver looking up at a coin above the water sees it higher than it really is, because light bends towards the normal as it enters the water (II). Both statements are correct. Remember: the apparent depth of an underwater object is less than its real depth.
- I. An underwater coin appears nearer the surface because of refraction.
- II. From under water, a coin above the surface appears higher than it is.
Why each option is right or wrong
- (a) Right. Both statements are correct.
- (b) Wrong. II is also correct.
- (c) Wrong. I is also correct.
- (d) Wrong. Both are correct.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 1999, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.