1.

A source of light is located at double focal length from a convergent lens. The focal length of the lens is f = 30 cm. At what distance from the lens should a flat mirror be placed, so that the rays reflected from the mirror are parallel after passing through the lens for the second time?

Answer»

SOLUTION :
Object is at DISTANCE of 2f = 60 cm from the LENS. Image formed by lens `I_1` should be at a distance 60 cm from the lens.
Now `I_2` the image formed by plane mirror should lie at focus or a distance of 30 cm from the lens.
Hence, the mirror should be placed at distance 45 cm from the lens as shown in figure.


Discussion

No Comment Found

Related InterviewSolutions