An object 240 cm in front of a lens forms a sharp image on a screen 12 cm behind the lens.
Channel: Doubtnut
Date: 2020-02-20

An object 240 cm in front of a lens forms a sharp image on a screen 12 cm behind the lens. A glass slab 1 cm thick, having refractive index 1.50 is placed between the lens and the screen with its refracting faces perpendicular to the principal axis of the lens. (a) By how much distance the object must be moved so as to again cast a sharp image on the screen? (b) Another identical glass slab is interposed between the object and the lens. How much further the object shall be moved so as to form a sharp image on the screen.