Question

A ray of light is incident normally on a plane glass slab. What will be the angle of deviation for the ray?

• A. $0^o$
• B. ${90}^o$
• C. ${180}^o$
• D. ${120}^o$

Answer 1

The correct option is A $0^o$

A ray of light incident normally on any medium will not undergo any refraction,hence no deviation is seen. According to Snell's law: $n_{1}sin{\theta }_1$=$n_{2}sin{\theta }_2$ where n represents the refractive index of the two mediums and $\theta$ the angle from the normal.
Thus, when ${\theta }_1$=0; $n_{2}sin{\theta }_2$=0 thereby implying that ${\theta }_2$=0