An object placed between the pole and focus of a concave mirror produced a virtual and enlarged image. Explain this using mirror formula.

Explanation

According to the spherical mirror formula
`(1)/(v)+(1)/(u)=(1)/(f)`
`(1)/(v)=(1)/(f)-(1)/(u)`
`(1)/(v)=(u-f)/(uf)`
For a concave mirror, f = - ve and u = - ve,
It is given that `u lt f` so v is positive.
Since `v gt 0` i.e. positive and `u lt 0` i.e. negative.
Therefore, image formed is behind the mirror [virtual].
`m=-(v)/(u)`
`m=-((+v))/((-u))` therefore m is + ve and the image is enlarged.