A concave mirror of focal length 15 cm forms an image having twice linear dimensions of the object. The position of the object when the image is virtual will be

Options

A. 22.5 cm
B. 7.5 cm
C. 30 cm
D. 45 cm

Answer

C

Explanation

For virtual image, m `= (-v)/(u) = + 2 or v = - 2u`
`As (1)/(u) + (1)/(v) = (1)/(f)`
`therefore(1)/(u)-(1)/(2u)=(1)/(-15)or(1)/(2u)=(1)/(-15)rArru=-7.5 cm`