Question

A point object is placed at a distance of`25cm`from a convex lens of focal length `20cm`.If a glass slab of thickness`t`and refractive index `1.5`is inserted between the lens and object.The image is formed at infinity .Find the thickness?

Answer 1

Correct Answer - `15cm`

For final image at infinity image by the stable must eb at the focus of convex lense shift=`t(1-(1)/(mu))rArr5=t(1-(2)/(3))`
`t=15cm`