A plano convex lens of refractive index 1.5 and radius of curvature 30cm. Is silvered at the curved surface. Now this lens has been used to form the image of an object. At what distance from this lens an object be placed in order to have a real image of size of the object.

Options

A. `20cm`
B. `30cm`
C. `60 cm`
D. `80 cm`

Answer

A

Explanation

Focal length of system (concave mirrorr )
`F=(R)/(2mu)=(30)/(2xx1.5)=10cm=10cm`
In order to have a real image of the same size of the object, object must be placed at centre of curvature `u=(2f)`.