Question

Pick the incorrect statements regarding the refractive index from the following.

• A. A higher refractive index means higher speed of light in the medium.
• B. A lower refractive index means an optically rarer medium.
• C. It is the measure of the extent of bending of a light ray in a medium with respect to another medium.
• D. It is the measure of the speed of a light ray in a medium with respect to another medium.

Answer 1

The correct option is A A higher refractive index means higher speed of light in the medium.

Refractive index of a medium with respect to another medium is defined as : $n=\frac{v_1}{v_2},$ where $v_1$ is the speed of light from which it enters and $v_2$ is the speed of the light in the medium into which it enters.
Also, the more the difference in the speed, the more higher or lower is the ratio and thus, more is the extent of bending. Hence, refractive index gives the measure for the degree or the extent of bending and at the same time compares the speed of the light in those media.
A lower refractive index means a higher value of $v_2$, which makes it an optically rarer medium.