Question

The image obtained with a convex lens is real and inverted and its length is 4 times the length ofobject. If the focal length of the lens is 20 cm, calculate the position of object and image. (3)​

Answer 1

Answer:

f=20cm

and v=40cm

v

1

−

u

1

=

f

1

⟹

40

1

−

u

1

=

20

1

⟹

u

1

=

40

−1

⟹u=−40cm

magnification m=

u

v

=

−40

40

=−1

Hence, the image formed is real , inverted and of same size as that of the object.