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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 it. Which of the above statements is/are correct ?
Explanation
Both statements are correct. When an observer in air looks at a coin submerged in water, refraction at the water–air interface bends emergent rays so they appear to come from a point nearer the surface; the coin therefore looks raised (closer) than its true depth [1]. Conversely, when an observer underwater looks up at a coin in air, rays from the coin refract toward the normal on entering water, so the apparent height of the coin measured from the water surface increases; formal application of Snell’s-law geometry gives d' = d·(n_water/n_air) (> d) so the coin appears at a higher level than its actual position [2].
Sources
- [1] Science , class X (NCERT 2025 ed.) > Chapter 9: Light – Reflection and Refraction > Activity 9.8 > p. 146
- [2] https://www.asc.ohio-state.edu/humanic.1/p112_lecture18.pdf
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