Question

A real image is produced which is 3 times enlarged by concave mirror when placed
at a distance of 20cm in front of it. What will the position of the image produced?​

Answer 1

Given,

Magnification, m=3

Object distance, u=10cm

We know,

Magnification, m=−

u

v

3=

−10

−v

⇒ v=30cm

From mirror formula,

f

1

=

v

1

+

u

1

f

1

=

30

1

−

10

1

=

30×10

10−30

=

300

−20

f=−15cm

Focal length, f=−15cm