An object O is placed at 7 cm to the left of a concave mirror of raidus of curvature 12 cm as shown in the figure. The position of the image will be at a distance of

Options

A. 20 cm from the mirror to the left.
B. 30 cm from the mirror to the right.
C. 42 cm from the mirror to the left.
D. 42 cm from the mirror to the right.

Answer

C

Explanation

Given, distance between object and mirror,
`u=-7cm`
Radius of curvature, `R=-12cm`
`:.` Focal length, `f=-(12)/(2)=-6cm`
From mirror formula,
`(1)/(v)+(1)/(u)=(1)/(f)`
Putting the given values,
`(1)/(v)+(1)/(-7)=(1)/(-6)`
`(1)/(v)=(1)/(-6)+(1)/(7)=-((1)/(6)-(1)/(7))`
`impliesv=42` cm
Hence, the position of the image will be 42 cm from the mirror to the left.