A convex lens is put 10 c m from a light source and it makes a sharp image on a screen, kept 10 c m from the lens. Now a glass block (refractive index 1.5) of 1.5 c m thickness is placed in between the light source and the lens. To get the sharp image again, the screen is shifted by a distance d . Then d is:

Step-by-step solution

From given data 1 v - 1 u = 1 f 1 10 - 1 ( - 10 ) = 1 f f = 5 c m When glass plate is placed, shift in object for lens s = t 1 - 1 μ = 1.5 1 - 2 3 = 0.5 c m Shift will be in the direction of incoming rays ∴ u = 10 - 0.5 = 9.5 c m 1 v - 1 u = 1 f 1 v = 1 5 + 1 ( - 9.5 ) v = 47.5 4.5 c m Shift = 47.5 4.5 - 10 = 2.5 4.5 = 5 9 c m = 0.55 c m away from lens.