Question

When an object is placed at a distance of 24cm in front of a concave mirror of focal length 12 cm , then image is formed (i) behind the mirror(ii) between the mirror and focus(iii) at the focus (iv) at centre of curvature of the mirror

Answer 1

Given

Object distance, u=24cm

Image distance, v=16cm

From mirror formula

f

1

=

v

1

+

u

1

f

1

=−

16

1

−

24

1

=−(

16×24

24+16

)

−

24

10

f=9.6cm= focal length

Radius of cuvature R=2f

=2×−9.6

=−19.2cm

magnification, m=−

u

v

=−

−24

−16

m=−2/3

Answer 2

${\rm{\red{\underline{\underline{\huge{Answer}}}}}}$

Concave mirror forms an image of the sun at a distance of 12 cm. So the focal length of mirror is 12 cm. Radius of mirror is For shaving we need to get a virtual image which should be magnified and erect. So the mirror must be kept at a reasonable distance of 8-10 cm which is within focus and pole. As the radius is 24cm the object placed at center forms image at the same place .