Question

An object of height 100 cm gives an image of 250 cm in front of the mirror. If the object is placed at 20 cm from the mirror, the position of the image will be

Answer 1

Explanation:

Step1: Applying Mirror Formula

Object distance u=−36 cm

Focal length of concave mirror f=−12 cm

Using mirror formula :

v

1

+

u

1

=

f

1

Or

v

1

+

−36

1

=

−12

1

⟹ v=−18 cm,

Since image position is negative, i.e. image is on the same side of object, which is real space, therefore the image is real.

Step2: Finding Height using Magnification

Magnification

h

o

h

i

=

u

−v

Or

10

h

i

=

−12

−(−18)

⟹ h i=−15 cm

Negative height implies that the image is inverted.

Hence, a real and inverted image of height 15 cm is formed at a distance of 18 cm in front of the mirror.