What best describes why the critical angle of an air-glass boundary is 39.3°?
a.
it is the angle of refraction in glass for which the angle of incidence in air is 90°.
b.
it is the angle of incidence in air for which the angle of refraction in glass is 90°
c.
it is the angle of refraction in air for which the angle of incidence in glass is 90°
d.
it is the angle of incidence in glass for which the angle of refraction in air is 90°.

A

Explanation:

When light is refracted, the sine of the angle changes in proportion to the refractive index. When the light is 90 degrees, the sine is zero, and zero is still zero on the other side. So nothing changes.

A.

It is the angle of refraction in glass for which the angle of incidence in air is 90°.

Explanation:

A critical angle is described as the angle of incidence provided that the angle of refraction is equal to 90 degrees. The value of the critical angle depend on factors such as the materials present on different sides of the boundary. The critical angle of glass-water boundary is 39.3 degrees.

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