Question

A stick of length 10 cm and negligible
thickness is placed parallel to the principal
axis in front of a curved mirror. The image
of this stick formed by the mirror is virtual
and appears 3 times longer than the
object. If the closest end of
the stick is at 20 cm from the
pole of the mirror, find the
type of mirror and its focal
length
please DonT Spam
​

Answer 1

focal length will be 5 and it's concave mirror. let see how

Given for the concave mirror :

Focal Length, f=−10cm

Length of the rod, L =10cm

Closer end distance of rod, u =- 20 cm

Far end distance of rod, u= -20-10=- 30 cm

By using mirror formula for end A:

you can find their ans

hope it's not helpful for you xd