Question

The focal length of a convex lens is
20 cm. The image formed is double the
length of the object. The distance of the
object from the lens is
(1) -30 cm.
(2) -20 cm.
(3) -60 cm.
(4) 30 cm.​

Answer 1

Answer:

f=20cm

and v=40cm

v1​−u1​=f1​

⟹401​−u1​=201​

⟹u1​=40−1​

⟹u=−40cm

magnification m=uv​=−4040​=−1

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

Explanation: