Question

size of the image of an object by a mirror having a focal length of 20 cm is observed to be reduced to 1\3 rd of its size in front of it. at what distance from the mirror the object has been placed ? what is the nature of the image and the mirror?

Answer 1

let size of object be x

size of image=x-(1/3)x = 2x/3

f=20cm given

using mirror formula

1/v+1/u=1/f

3/(2x)+1/x=1/20

5/(2x)=1/20

x=50

concave mirror

image is

inverted

smaller then object