# Refraction takes place at a concave spherical boundary separating glass air medium. For image to be real the object distance $(\mu g=\large\frac{3}{2})$

(a) Should be greater than 3 times the radius of curvature of refracting surface.

(b)Should be greater than 2 times the radius of curvature of refracting surface.

(c) Should be greater than radius of curvature of refracting surface.

(d)Is independent of radius of curvature of refracting surface

Applying $\large\frac{\mu_2}{v}- \frac{\mu_1}{u}=\frac{\mu_2 -\mu_1}{R}$
$\large\frac{1}{v}-\frac{1.5}{(-u)}=\frac{(1-(1.5)}{-R}$
or $\large\frac{1}{v}+ \frac{3}{2u}=\frac{1}{2R}$
For v take +ve $\large\frac{1}{2R} > \frac{3}{2u}$
or $u > 3R$
Hence a is the correct answer.