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

Options

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

Answer

Converging; real

Explanation

`v = (uf)/(u-f) = ((-15) xx (-10))/(-15+10) = -30cm, m = -(v)/(u) = -2, :. A'B' = C'D' = 2xx1 = 2mm`
Now `(B'C')/(BC) = (A'D')/(AD) = (v^(2))/(u^(2)) = 4 rArr B'C' = A'D' = 4mm`
`:.` Perimeter length `= 2 + 2 + 4 + 4 = 12mm`