14. An object is 12 cm in front of a concave spherical mirror, and the image is 3 cm in front of the
問題詳情
14. An object is 12 cm in front of a concave spherical mirror, and the image is 3 cm in front of themirror. What is the focal length of the mirror? (A) 0.25 cm (B) 1.5 cm (C) 2.4 cm (D) 4 cm (E) 13 cm