Question

An object is placed at a distance of 100cm from a converging lens of focal length 40cm.what is the nature of the lens,what is the position of the lens, which defeet of the eye can be removed by this type of lens

Answer 1

we have the values given as

object distance (u)=100cm

focal length (f)= 40cm

we have to find

image distance (v)

and the defect which can be removed from this type of lens

Solution: (1) by lens formula , we have

1/f=1/v -1/u

1/40=1/v-1/100

1/v=1/40+1/100

1/v=5/200+2/200(by taking LCM)

1/v=7/200

v=200/7

v=28.57cm

(2) the lens given is converging ,ie, convex lens . And it is used to remove a defect called as myopia