Question

A wavefront $AB$ is refracted from medium $1$ to medium $2$. The refractive index of medium $2$ is less than that of medium $1$. Which of the following wavefronts in medium $2$, show the refracted wavefront?

• A. $i=r$
• B. $i<r$
• C.
• D.

Answer 1

The correct option is B $i<r$

Since ${\mu }_2<{\mu }_1$, the speed of light is more in medium 2. The width of a plane wavefront is more in denser medium and less in a rarer medium. So, the wavefront $CD$ forms away from the surface as compared to $AB$ and $r>i$.

Therefore, for incident wavefront $AB$ the refracted wavefront $CD$ can be drawn as follows.

Hence, $\left(B\right)$ is the correct answer.

$\begin{array}{c}\text{Why this question?}\\ \text{Note:- Light travels faster in the medium which is less denser.}\end{array}$