Question

An object is placed 3 metre away from the lens which forms it's image at a distance of 1 metre on the same side where the object is placed.find the power of the lens what is the type of lens used???

Answer 1

Distace of the object , u= -3m

Distance of the image , v=-1 m

let focal length be f m

Lens formula ,

1/f=1/v-1/u

1/f =-1/1+1/3

1/f=(-3+1)/3

1/f=-2/3

f=-3/2

f-1.34m

Power of lens,

P=1/f

P = 1/-1.34

P= -0.74 D

This is a Concave lens