Question

A 10 mm long awl pin is placed vertically in front pin is formed at 30 cm in front of the mirror the focal length is

Answer 1

Answer:

It is given that the image is formed 30cm in front the mirror.

∴v=−30cm

Also magnification, m=

object height

image height

⇒m=

10mm

5mm

=

2

1

Again, m=

u

v

∴

u

−30

=

2

1

⇒u=−60cm

The mirror formula is given as,

f

1

=

v

1

+

u

1

⇒

f

1

=

−30

1

+

−60

1

⇒

f

1

=

60

−2−1

=−

60

3

=−

20

1

f=−20cm