An object is kept on the principal axis of a concave mirror of focal length 12 cm. If the object is at a distance of 18 cm from the mirror, calculate the image distance. Determine the nature of the image formed by calculating the magnification produced by the mirror.

Explanation

Given, Focal length of concave mirror `f=-12` cm and Object distance `u=-18` cm.
`(1)/(f)=(1)/(u)+(1)/(v)`
`(1)/(v)=(1)/(f)-(1)/(u)=-(1)/(12)-(-(1)/(18))=-(1)/(12)+(1)/(18)=(-3+2)/(36)`
`therefore (1)/(v)=-(1)/(36)rArr v=-36 cm`.
Magnification `m=(-v)/(u)=-((-36)/(-18))=-2`
The image formed is inverted real and enlarged.