UPSC CDS 2 2020 GK Paper

In this case, the angle of incidence is 0° and
sin‌θ2=

n1

n2

‌sin‌θ1=0
∴θ2=0
In this case, the angle of incidence is 0°. This diagram shows that if the light ray is incident at 0°, then the angle of refraction is also . There is no change in the direction of the light ray, thus, the speed of the light will change as it moves into the new medium.