Question

Draw a labelled ray diagram for the formation of image by a convex lens of focal

length 15 cm when the object is place.

Answer 1

let distance of object be u,image be v,height of object be Ho and height of object be He.

u=-25cm

f=15cm

then

1/f=1/v-1/u

1/v=1/f+1/u

=1/15-1/25

=(5-3)/75

=2/75

then

v=75/2

=37.5cm

He/Ho=v/u

He=v/u*Ho

=37.5/-25*4

=-6

height of image is 6cm inverted.

I hope it will help you.

Thanks