Question

the focal length of a convex lenses is 10 cm. at what maximum distance can the image of an object be formed

Answer 1

Given,

Focal length=f=10cm

Image distance=v=20cm

Using sign convention,

f is positive,v is also positive

Lens formula,

1/f=1/v-1/u

1/10=1/20–1/u

1/u=1/20–1/10

1/u=(10–20)/200

1/u=-10/200

u=-20

Object distance=20cm(minus indicates that the lens is converging lens)

Hope it helps....

Answer 2

Answer:

the answer is 20cm

Explanation:

for explanation see the picture