Assertion (A) > : Small glass beads fixed on traffic signals glow brightly when light falls upon them. Reason (R) > : Light is totally reflected when the angle of incidence exceeds a certain critical value and light travelling in a denser medium is reflec

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Q: 105 (IAS/2000)

Assertion (A) : Small glass beads fixed on traffic signals glow brightly when light falls upon them.
Reason (R) : Light is totally reflected when the angle of incidence exceeds a certain critical value and light travelling in a denser medium is reflected from a rarer medium.

question_subject: 

Science

question_exam: 

IAS

stats: 

0,37,18,37,10,8,0

keywords: 

{'traffic signals': [0, 1, 0, 0], 'light': [16, 4, 34, 62], 'small glass beads': [0, 1, 0, 0], 'denser medium': [0, 1, 0, 3], 'incidence': [1, 1, 3, 3], 'angle': [0, 0, 1, 0]}

The Assertion (A) states that small glass beads fixed on traffic signals glow brightly when light falls upon them. This is correct as the beads reflect light due to the phenomenon of total internal reflection. The Reason (R) provides an explanation for this phenomenon. It accurately states that light is totally reflected when the angle of incidence exceeds a certain critical value and when light, traveling in a denser medium hits the boundary of a rarer medium. This is the basic principle of total internal reflection, which is why the small glass beads glow brightly when light falls upon them. Therefore, option 1 is the correct answer because both A and R are true, and R correctly explains A.