Question

Where an object should be placed in front of a concave mirror so as to get unit magnification?

Answer 1

Let f is the focal length of concave mirror. an object is placed at u distance from the pole of concave mirror.

a/c to question,

magnification = 1

we know, magnification of mirror, m = -v/u

or, -v/u = 1

or, v = -u......(1)

now, from mirror formula,

1/v - 1/u = 1/f

from equation (1),

or, 1/-u - 1/u = 1/f

or, 2/-u = 1/f

or, u = -2f = -R [ we know, R = 2f, where R is radius of curvature of mirror ]

hence, when the object is placed at radius of curvature of mirror, image also forms at radius of curvature.

Answer 2

Answer:

at centre of curvature

Explanation: