Question

A convex mirror has a focal length=20cm. A convergent beam tending to converge at a point 20cm behind convex mirror on principal axis falls on it. The image if formed at

Answer 1

Answer:

The answer will be 10 cm

Explanation:

According to the problem the focal length of the mirror is given, let it be f

Therefore f = -20 cm

The beam has converged at 20 cm behind the mirror

therefore

u = 20 cm

let the image will form at v distance

Now we know that,

1/f = 1/u + 1/v

-1/20 = 1/20 + 1/v

= 1/v = 1/10

v = 10 cm

Answer 2

Answer:

ans is 10

Explanation:

According to the problem the focal length of the mirror is given, let it be f

Therefore f = -20 cm

The beam has converged at 20 cm behind the mirror

therefore

u = 20 cm

let the image will form at v distance

Now we know that,

1/f = 1/u + 1/v

-1/20 = 1/20 + 1/v

= 1/v = 1/10

v = 10 cm