A square ABCD of side 1mm is kept at distance 15cm in front of the concave mirror as shown in Figure. The focal length of the mirror is 10cm. The length of the perimeter of its image will be

Options

A. 8mm
B. 2mm
C. 12mm
D. 6mm

Answer

c.

Explanation

`v=-30, m=-(v)/(u)=-2`
`rArr A^(')B^(')=CD=2xx1=2mm`
Now, ` (B^(')C^('))/(BC)=(A^(')D^('))/(AD)=(v^(2))/(u^(2))=4`
`rArr B^(')C^(')=A^(')D^(')=4mm`
`:.` Length `=2+2+4+4=12mm`