Q. The focal length of a concave mirror is $f$ and the distance from the object to the principle focus is $x$. The ratio of the size of the image to the size of the object is
A) $\frac{f + x}{f}$
B) $\frac{f}{x}$
C) $\sqrt{\frac{f}{x}}$
D) $\frac{f^{2}}{x^{2}}$
Explanation
(b) $\frac{I}{O} = \frac{f}{f - u};$ where $u = f + x\ \ \therefore\frac{I}{O} = - \frac{f}{x}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.