The image of a small electric bulb fixed on wall of a room is to be obtained on opposite wall of a room 3m away by means of large convex lens. What is the maximum possible focal length of the lens required for this purpose?

Asked by Sourav Naval | 1st Jun, 2014, 01:53: PM

Expert Answer:

For a certain fixed distance x between object and screen, the lens equation does not give a real solution for u or v if f is greater than x/4.

So, maximum focal length is 0.75 m.

Answered by Faiza Lambe | 2nd Jun, 2014, 08:21: AM