Question

b) State the condition under which no change in the direction of propagation
of a light ray would take place when it passes from Medium A toMedium B.
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Answer 1

If the incident ray follows the normal drawn perpendicularly on the junction plane of 2 mediums, it will not refract. Angle of refraction (angle between the refracted ray and the normal), 'r' also becomes 0 thus no change in direction occurs.