del CUTTU
A ray of light passes from vacuum into a medium of refractive index u. If the angle of incidence is
twice the angle of refraction, then the angle of incidence is
(A) cos "(112)
(C)2 cos (2) Mein
(D)2sin (2)
(B) sin'(142)
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Answers
Answered by
1
Let i be the incident angle and r be the refracted angle
given, 1=2r⇒r=
2
i
the refractive index of vacuum is 1 and that of another medium is n
from snell's law,
1sini=nsinr
⇒sini=nsin(
2
i
)
2sin(
2
i
)cos(
2
i
)=nsin(
2
i
)
⇒sin(
2
i
)[2cos(
2
i
)−n]=0
sin(
2
i
)=0=sinπ⇒i=2π
[2cos(
2
i
)−n]=0⇒i=2cos
−1
(
2
n
)
therefore the value of incident angle =2cos
−1
(
2
n
)
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