Practice portal › Ray Optics and Optical Instruments › Refraction and Total Internal Reflection
Asked in GSEB Board July 2021 · Snell's law, slabs and apparent depth
Given: the earth turns through 360° in 24 h, and the sun is to shift by 2°.
Idea: the sun's apparent march across the sky is simply the earth's rotation seen from the ground, so angle and time are in direct proportion.
24 h = 24× 60 = 1440 min for the full 360°.
One degree therefore takes (1440)/(360) = 4 min.
Two degrees take 2× 4 = 8 min.
This is the arithmetic behind the textbook statement about atmospheric refraction: it lifts the sun by about half a degree, which buys roughly two extra minutes of daylight at each end of the day.
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