Question Detail
Question
A concave mirror has radius of curvature 12 cm. At what distance from the mirror should an object be placed to give a virtual image three times the object size?
Correct Answer
Option D is the correct answer.
Detailed Explanation
For a virtual image, m = +3. m = -v/u = 3 => v = -3u. f = R/2 = 6 cm. Mirror equation: 1/f = 1/u + 1/v => 1/6 = 1/u + 1/(-3u) = 1/u - 1/(3u) = 2/(3u). u = 2 × 6 / 3 = 4 cm.
Hint
Use m = -v/u and the mirror equation.