Question

:A 2 cm high object is placed at a distance of 32 cm from a concave mirror.the image is real inverted and 3 cm in size. Find focal length of the mirror and position of the image.​

Answer 1

Explanation:

Image is inverted so magnification must be negative.

m=

objectheight

imageheight

=

2

−3

=−1.5

Also object distance is u=−32cm

We know m=−

u

v

−1.5=−

−32

v

Position of object from lens is v=−48cm

We know

f

1

=

v

1

+

u

1

f

1

=

−48

1

+

−32

1

f=−19.2cm