Question

if an object is placed 30 cm from a convex lens whose focal length is 15 cm the size of the image compared to the size of object will be approximately...?​

Answer 1

Answer:

u = 30 cm (negative)

f = 15 cm (positive)

From the formula:-

1/f = 1/v - 1/u

1/15 = 1/v - 1/(-30)

1/15 = 1/v + 1/30

1/15 - 1/30 = 1/v

2-1/30 = 1/v

1/30 = 1/v

⇒ v = 30 cm (positive)

Now:

Size of image/ Size of object = I/O = -v/u

-30/-30 = 1/1

∴ The size of image is in ratio with size of object = 1:1

Explanation:

Hope it helps you buddy :)