Question

a convex lens at a focal length 10 cm at what distance should the object be placed show that it forms a real and inverted image 20 cm away from the lens. what would be the size of the image formed if the object is 20cm high.

Answer 1

the distance of the object is -20 cm and height of the image formed is -20cm

Answer 2

f=10cm

V= -20cm

U=?

M=?

1/v-1/u=1/f

-1/20-1/u=1/f

-1/u=3/20

U=-20/3

Now m=v/u

= -20/-20/3

=3cm

Therefore m=3cm

U=-20/3 cm