Find the angle of incidence for which angle of deviation from a liquid drop is minimum in a primary rainbow
Text Solution
Verified by ExpertsThe correct answer is:
D
sin i = µ sin r … (1)
differentiating eq. (1) cos i di = µ cos r dr
or 
= 
= 
or 2 cos i = µ cos r
or 4 cos 2 i = µ 2 cos 2 r = µ 2 (1 – sin 2 r)
or 4 cos 2 i = µ 2 
= µ 2 – (1 – cos 2 i)
or 3 cos 2 i = µ 2 – 1
or cos i = 
= 
= 
or cos i = 
= .5
or i = 60 0 .
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