Question

A convex mirror of focal length f produces an image (1/n)th of the size of the object. The distance of the object from the mirror is(a) (n – 1)f(b) f/n(c) (n + 1)f(d) nf

Answer 1

What last line means

Answer 2

The mirror formula is 1v+1u=1f, where v,u and f are the distances of the image and object from the mirror and the focal length respectively.

focal length = f

magnification = 1/n

Let object was placed at a distance u = x

Since, m = |v/u|

=> v = x/n

Applying mirror formula and using the values of u,v and f we get

-1/x + n/x = 1/f

n-1/x = 1/f

x = f(n-1)

The distance of the object from the mirror is |u|=f(n−1).