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`