Question

An object is placed at a certain distance from a convex lens of focal length 20 cm. Find the distance of the object if the image obtained is magnified 4 times.

Answer 1

Answer:

10cm

Explanation:

An object is placed at a certain distance from a convex lens of focal length 20 cm. Find the distance of the object if the image obtained is magnified 4 times.

Answer 2

Answer:

u=-15cm

Explanation:

f=20cm

m=4=v/u

lens formula,1/u-1/v=1/f

1/4u-1/u=1/20

1-4/4u=-3/4u

-3/4u=1/20

4u=-60

u=-60/4

u=-15