Question

Assertion (A) : Refractive index has no units.
Reason (R) : Refractive index is ratio of two similar quantities.

• A. Both A and R are true and R is the correct explanation of A
• B. Both A and R are true and R is not the correct explanation of A
• C. A is true but R is false
• D. A is False but R is true

Answer 1

The correct option is A Both A and R are true and R is the correct explanation of A

Absolute refractive index of a medium is given by:
$n=\frac{c}{v}$
where:
$c:$ Speed of light in vacuum
$v:$ Speed of light in medium

Since it is the ratio of same quantity (speed), it is unitless.

So, the assertion and reason, both are correct. Reason explains the assertion.