Question

. (a) A divergent lens has a focal length of 20 cm. At what distance should an object of
height 4 cm from the optical centre of the lens be placed so that the image is formed 10
cm away from the lens. Also find the size of image formed.​

Answer 1

here f is given 20 cm  

        O =4.0 [POSITIVE]

        v=10cm  [-ve]

        1/v-1/u=1/f

      =  -1/u=1/v-1/f

         -1/u=1/10-1/20

          =2/20-1/20=1/20

so -1/u=1/20 and u=-20

I/O=v/u and so I=v/u*O=-10/-20*4

      therefore I=2

pls mark as brainliest hope it helps u