Question

A conveying mirrors forms a real image of height 4cm of an object of height 1cm placed 20cm away the mirror.Calculate the image distance and focal length of the mirror

Answer 1

Answer:

hi = 4cm

ho = 1cm

u=-20cm

v=?

hi/ho=-v/u

where,

hi=height of the image

ho=height of the object

v=distance of the image from the mirror

u=distance of the object from the mirror

4/1=-v/-20

4 = v/20

v = 80cm

Let focal length of the mirror to be 'f'

1/f = 1/v + 1/u

1/f = 1/80 + 1/(-20)

1/f = 1/80 - 1/ 20

1/f = -3/80

f = -80/3 cm