Question

An object is placed at f/2 away from first focus of convex lens where f is the focal length of the lens.
Its image is formed at a distance 3f/2 in a slab of refractive index 3/2, from the face of the slab facing
the lens. Find the distance of this face of the slab from the second focus of the lens.
1).f/2
2) 3f/2
3) 2f
4) f​

Answer 1

Answer:

f

Explanation:

Given An object is placed at f/2 away from first focus of convex lens where f is the focal length of the lens.

Its image is formed at a distance 3f/2 in a slab of refractive index 3/2, from the face of the slab facing  the lens. Find the distance of this face of the slab from the second focus of the lens.

Now given

u = - (f + f/2)

  = - 3 / 2 f

From one face of the slab distance of final image is 3/2 f.

Now distance of image formed due to convex lens from face of the slab is

  f = 3/2 f / μ       (μ = 3/2)

 Let F2S = x

v = 2f + x

We know that 1/f = 1/v – 1/u

1/f = 1/(x + 2f) – 1/(-3f/2)

x = f