Question

A small candle 2.5 cm in size is placed 27 cm in front of a concave mirror of radius of curvature 36 cm. At what distance from the mirror should a screen be placed in order to obtain a sharp image? Describe the nature and size of the image. If the candle is moved closer to the mirror, how would the screen have to be moved?

Answer 1

Answer:

162 cms

Explanation:

$\frac{1}{v}+\frac{1}{u}=\frac{1}{f}$(Mirror formula)

v=-27cms. r=-36cms

(mind the sign convention. In front of the mirror is negative; inside the mirror is positive.)

Plug values into formula.

$\frac{1}{v}+ \frac{-1 cms}{27}=\frac{1 cms}{36}$

we get V=  162 cms approx behind of the mirror.

The image is virtual and magnified and erect.

If object is moved closer to mirror, screen would have to be moved exponentially into the mirror further.