A spherical surface of radius 30 cm separates two transparent media A and B with refractive indices 1'33 and 1.48 respectively. The medium A is on the convex side of the surface. Where should a point object be placed in medium A so that the paraxial rays become parallel after refraction at the surface ?

Answer

`-266 cm`

Explanation

Here, `mu_1 = 1.33, mu_2 = 1.48, u = ?, v = oo`
`R = 30 cm`
Refraction from rarer to denser medium
`-(mu_1)/(u)+(mu_2)/(v)=(mu_2 - mu_1)/( R)`
`-(1.33)/(u)+(1.48)/(oo)=(1.48 - 1.33)/(30)=(0.15)/(30)=(1)/(200)`
`u = -200 xx 1.33 = -266 cm`.