Question

An object of height 2 cm is kept at a distance of 20 cm in front of a concave mirror and its virtual erect image is formed 60 cm behind the mirror . calculate the size of the image .​

Answer 1

Answer:

-3 cm

Explanation:

Size of object  ho=2cm

Size of the object  hi=?

Focal length  f=−12cm

Object distance  u=−20cm

Image distance  v=?

Using mirror formula

f1=v1+u1

−121=v1+−201

v1=60−5+3

v=−30cm

Magnification (M)=hohi=u−v=−2030=−1.5

hi=−1.5×2=−3cm

Image will be real, inverted and magnified.

Answer 2

Answer:

We have,

Object distance=u= -20 cm

Image distance=v=+60 cm( By

sign convention)

Height of object=ho=2 cm

Height of image=hi

We know that,

Magnification=-v/u=hi/ho

Therefore,

-60/-20=hi/2

or,hi=3x2=6 cm

Hence,the size(height) of the

image is 6 cm.