Question

Find the position, nature and size of the image of an object 4 cm high placed at a

distance 10 cm from a concave mirror of focal length 20 cm.​

Answer 1

Answer:

see below

Explanation:

u= -10cm

f=-20cm

h=4cm

v=?

H(height of image)=?

1/v + 1/u = 1/f

1/v + 1/-10 = 1/-20

1/v = -1/20+2/20 (after simplification)

1/v = 1/20

v=20cm

m=-v/u=H/h

-20/-10=H/4

H=8

As v and H are positive, the image formed is virtual and enlarged(H>h)

If you have more doubts ask me or refer sign convention,