Question

A point object is placed at a distance of 25cm from a convex lens. Its focal length is 22cm. A glass slab of refractive index 1.5 is inserted between the lens and the object, then the image is formed at infinity. Find the thickness of the glass slab (in cm).

Answer 1

Correct Answer - 9
When object is placed at the focus of the lens, i.e., at 22cm from the lens, image will be formed at infinity. Shift in the positino of object`:`
`25-22=(1-(1)/(mu))t`
`rArr3=[1-(1)/(1.5)]trArrt=((3)(1.5))/(0.5)=9cm`