An object `1cm` tall is placed `4cm` in front of a mirrorr. In order to produce an upright image of `3cm` height one needs a

Options

A. convex mirror. `R=12cm`
B. concave mirror `R=12cm`
C. convex mirror, `R=4cm`
D. plane mirror of height `12cm`

Answer

B

Explanation

Image is erect and enlarged, mirror is concave
`(I)/(O)=-(v)/(u)implies(3)/(1)=-(v)/(-4)`
`v=12cm`
`(1)/(f)=(1)/(v)+(1)/(u)=(1)/(12)+(1)/(-4)=(1-3)/(12)=-(1)/(6)`
`f=-6cm` , `R=-12cm`
Concave mirror of radius of curvature `=12cm`