Question

What is the angle of incidence if a ray of light is not deviated when it enters a block of glass?

• A. ${30}^{\circ }$
• B. ${60}^{\circ }$
• C. ${90}^{\circ }$
• D. $0^{\circ }$

Answer 1

Answer: (D)

The angle of incidence if a ray of light is not deviated when it enters a block of glass :

The angle of incidence is equal to angle of refraction only if the angle the deviation is zero. This is practically impossible since, when light enters a medium from another medium it has to undergo refraction. So angle of minimum deviation is never zero but it can be a very small value. And angle of incidence is never equal to angle of refraction, if the light undergoes minimum deviation. But the angle of incidence is equal to the angle of emergence.