If ray travelling in air is incident on a transparent medium as shown in the diagram, the refractive index of the medium is given as
-
A.
cosα / sinβ -
B.
sinα / sinβ -
C.
cosβ / sinα -
D.
sinβ / sinα
Correct Answer: Option A
Explanation
(n = frac{sin i}{sin r})
(i = 90 – alpha)
(therefore n = frac{sin 90 – alpha}{sin beta})
⇒ (n = frac{cos alpha}{sin beta})