Q.The image produced by a concave mirror is one- quarter the size of object , if moved 5 cm closer to the mirror, the image will only be half the size of the object. The focal length of mirror is
(a) f = 5.0 cm
(b) f = 2.5 cm
(c) f = 7.5 cm
(d) f = 10 cm
Ans: B