Question

What is the power of lens of focal
length +20 cm, Also find the nature of the lens.​

Answer 1

Focal length f=−20 cm

Object distance u=−50 cm

Using

1/v − 1/u = 1/f

Or

1/v −1/(−50)= −1/20

We get v=−14.3 cm

Since, v is negative. So image formed is virtual.

Hence, virtual image is formed at a distance of 14.3 cm in front of the lens.

Answer 2

Answer:

Explanation:

The power of lens=1/focal length

The power=1/+20=+0.05

The lens is concave since its position is towards the direction of incident ray from origin