Question

Rohit places pencil perpendicular to principal axis in front of a converging mirror of length 30 cm the image formed is twice the size of the pencil calculate the distance of the object from the mirror

Answer 1

yes,

so twice the size will be 30×2

then divide it by 5

Answer 2

Answer:

Magnigfication = hi / ho = -v / u

We can assume it to be virtual because in a concave mirror, it is enlarged only when it is virtual. Otherwise, if you refer to the ray diagrams, they are all diminished.

The remaining procedure is correct, wherein we get -v /u = 2

So, if v = - 2u.

Using the mirror equation,  

1 / v + 1 / u = 1 /f

= -1 / 2u + 1 / u = 1 / -30

u = - 15 cms. which is between the focal length and the mirror. This proves that the image will be virtual and enlarged.

Explanation: