Question

A mirror having focal length 10cm forms inverted image 1/5 size of object . Find u,v and nature of image

Answer 1

To start with, Since image is inverted, We expect the mirror to be Concave mirror.

In case of concave mirrors, Focal length is negative, Object distance is also negative. Image distance is also negative for inverted images.

Given, hi = 1/5 ( ho)

Focal length f = - 10 cm

Since it's concave mirror with inverted image,

So, m = hi/ho = - 1/5

It is also known, m = - v/u = - 1/5

which gives 5v = u

Apply mirror formula,

1/f = 1/v + 1/u

1/f = 1/v + 1/5v

1/f = 1/v +1/5v

1/f = 5+1/5v

1/-10 = 6/5v

-10 × 6= 5v

v = - 60/5 = - 12

Therefore, v = - 12 cm, u = 5(-12)= - 60cm

Characteristics of image formed

1. Image is real
2. Image is inverted
3. Image is diminished
4. Image formed below the principal axis and between F & C
5. Image can be taken onto the screen.