Question

An object is kept 40cm in front of a concave mirror of focal length 20cm.find the position and nature of the image. Draw a ray diagram to show the formation of image in this case.

Answer 1

The image of infinity and if its at 2f the image will come to 2f using the mirror relation with the1/v + 1/u = 1/f

So 1/v = 1/f - 1/u , = 1/15 - 1/20

5/(15x20)= 1/60 therefore v= 60 cm

So the image will be formed at 60 cm

With magnification m= v/u = 60/20 = 3

the image will be 3 times larger and real