Question

A concave lens has focal length of 20 cm. At what distance from the lens a 5 cm tall object be placed so that it forms an image at 15 cm from the lens? Also calculate the size of the image formed.​

Answer 1

Answer:

$answer$

F--20

H¹-20 cm

v--15cm( convance lens from the virtual images)

Explanation:

1/v-1/ u-1/f

1/-15 -1/u =1/-20

1/u=-(1/15) +(1/20)

1/u--1/60

u=-60

object should be placed 60 cm to left of the lens

1/-u=1/60

u--60 cm

object should be placed 60 cm to the left of the lens

m=v/u -h2/5

h2 - 1.25 cm

image formed1. 25 cm high