Refraction takes place at a convex spherical boundary separating glass-air medium. For the image to be real, the object distance `(mu_(g)=3//2)` should be `//`is

Options

A. greater than three times the radius of curvature of the refracting surface
B. greater than two times the radius of curvature of the refracting surface
C. greater than the radius of curvature of the refracting surface
D. independent of the radius of curvature of the refracting surface

Answer

a.

Explanation

Applying`(mu_(2))/(v)-(mu_(1))/(u)=(mu_(2)-mu_(1))/(R)`
`(1)/(v)-(1.5)/((-u))=(1-(1.5))/(-R)` or `(1)/(v)+(3)/(2u)=(1)/(2R)`
For v to be positive, `(1)/(2R) gt (3)/(2u)`
or `u gt 3R`