A small candle 2.5 cm in size is placed at 27 cm in front of a concave mirror of radius of curvature 36 cm. At what distance from the mirror, should a screen be placed in order to obtain a sharp image.

Question

A small candle 2.5 cm in size is placed at 27 cm in front of a concave mirror of radius of curvature 36 cm. At what distance from the mirror, should a screen be placed in order to obtain a sharp image. (A) 36 cm (B) 48 cm (C) 54 cm (D) 60 cm

Tardigrade Admin · Accepted Answer

f=(R/2)=(-36/2)=-18 cm (1/v)+(1/u)=(1/f) (1/v)+(1/(-27))=(1/(-18)) ⇒ v=-54 cm

Q. A small candle $2.5 c m$ in size is placed at $27 c m$ in front of a concave mirror of radius of curvature $36 c m$ . At what distance from the mirror, should a screen be placed in order to obtain a sharp image.

36 cm

48 cm

54 cm

60 cm

$f = \frac{R}{2} = \frac{- 36}{2} = - 18 c m$
$\frac{1}{v} + \frac{1}{u} = \frac{1}{f}$
$\frac{1}{v} + \frac{1}{( - 27 )} = \frac{1}{( - 18 )}$
$\Rightarrow v = - 54 c m$

Q. A small candle 2.5cm in size is placed at 27cm in front of a concave mirror of radius of curvature 36cm. At what distance from the mirror, should a screen be placed in order to obtain a sharp image.