Question

An object of height 2.5 cm is placed at a distance of 10 cm in front of a concave mirror of focal length 5 cm.

Find by calculation :-

(i) the position,

(ii) the height and

(iii) the nature of the image formed.​

Answer 1

Answer:

Given that,

Distance u=−10cm

Height h=2.5cm

Radius of curvature R=30cm

We know that,

−f=

2

R

−f=

2

30

f=−15cm

Now, using mirror’s formula

f

1

=

v

1

+

u

1

−

15

1

=

v

1

−

10

1

v

1

=−

15

1

+

10

1

v=30cm

Now, the magnification is

m=

u

−v

m=

10

30

m=3

We know that,

m=

h

h

′

3=

2.5

h

′

h

′

=7.5cm

Hence, the size of the image is 7.5 cm