Question

9. The image is formed at a distance of 30 cm when the object is kept at certain distance from the concave mirror of focal length 15 cm. Then the object distance is too cm ( ) A) 15 B) 30 D) 25 0 o 19720​

Answer 1

Answer:

Given,

Focal length, f=15cm

Object distance, u=25cm

Object height, h

0

=4cm

From mirror formula,

f

1

=

v

1

+

u

1

−15

1

=

−25

1

+

v

1

⇒

v

1

=

−15

1

+

25

1

v=−37.5cm

magnification, m=−

u

v

=

h

0

h

i

⇒m=−

−25

(−37.5)

=

4

h

i

h

i

=−

25

37.5×4

h

i

=−6cm

To get a sharp image, v=37.5cm

The image is real, inverted and magnified