Question

4. Rohit focussed the image of a candle flame on a white screen using a convex lens. He noted
down the postion of the candle , screen and lens as under:-
position of candle = 26.0cm
position of convex lens =50.0cm
position of screen=74.0cm
(i) What is the focal length of the convex lens?
(2)
(ii) Where will the image be formed if he shifts the candle towards the lens at a postion of 38cm?​

Answer 1

Answer:

1)focal length is 12 cm

2)if candle is moved to 38cm, then image will be formed at infinity.

Explanation:

Note:To calculate the object and image distance, subtract the numerals, like in Q. 1) to calculate obj distance, I subtracted 26 from 50, always make a rough figure to get an idea of the question.