Question

In handheld optical instrument used under water light is incident from water onto the plane surface of crown glass atanangke of incidence of 45

(A) what is the angle of reflection of light off the crown glass

(B) does the refracted ray bend toward or away from the normal ?

(C) what is the angle of refraction in the crown glass ?

Answer 1

Solution,

A)

From the law of reflection, the reflected light must head off at an angle of 45 degree with the normal.

Reason: The angle of reflection is not dependent on the refractive indexes of the two media.

B)

Refractive index of water is 1.33 and for flint glass it is 1.63. Thus, light is moving from a lower to a higher index of refraction and will bend toward the normal.

C)

From Snell's law,

n1 sin(i) = n2 sin(r)

Sin(r) = 1.33 x sin45/1.63 = 0.577

Angle, r = arcsin(0.577) = 35.24 degree

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