SAT Subject Physics Practice Question 124: Answer and Explanation
7. An object is placed 60 cm in front of a concave spherical mirror whose focal length is 40 cm. Which of the following best describes the image?
Nature of image Distance from mirror
A. (A) Virtual 24 cm
B. (B) Real 24 cm
C. (C) Virtual 120 cm
D. (D) Real 120 cm
E. (E) Real 240 cm
Correct Answer: D
If so = 60 cm and f = 40 cm, the mirror equation tells us that
and, since si is positive, the image is real.