What curvature must be given to the bounding concave surface of refracting medium `(mu = 3//2)` for a virtual image at `40 cm` of an object in this medium at a distance of `60 cm`. The adjoining medium is air `(mu = 1)`.

Explanation

Here, `R = ? mu_2 = 3//2, v = -2, v = -40 cm, u = -60 cm, mu_1 = 1`
As refraction occurs from denser to rarer medium, therefore, `-(mu_(2))/(u) +(mu_(1))/(v) = (mu_(1) - mu_(2))/( R)`
`- (3)/(2(- 60)) + (1)/(-40) = (1 - 3//2)/( R), - (1)/(40)-(1)/(40)= -(1)/(2 R), - (1)/(20) = -(1)/(2 R)`
`R = 10 cm`.