Question

Solve: An object is kept 60 cm from a lens gives a virtual image
20 cm in front of the lens. What is the focal length of the lens? Is it
a converging lens or diverging lens.​

Answer 1

Answer:f=u+v

f=60+20=80

It is converging lens

Explanation:

Answer 2

Answer:

Data:u= -60 cm,v=-20 cm,f=?

1/f=1/v=1/u

=1/-20 cm-1/-60cm

=-(1/20cm-1/60cm)

=-(3-1/60 cm)

=-2/60cm

=-1/30 cm

Therefore,the focal length of the lens,f=-30cm.

As f is negative,it is a diverging lens.