Optics Question 794
Question: A short linear object of length i lies along the axis of a concave mirror of focal length f at a distance u from the pole of the mirror. The size of the image is approximately equal to
Options:
A) $ \ell {{( \frac{u-f}{f} )}^{1/2}} $
B) $ \ell {{( \frac{u-f}{f} )}^{2}} $
C) $ \ell {{( \frac{f}{u-f} )}^{1/2}} $
D) $ \ell {{( \frac{f}{u-f} )}^{2}} $
Show Answer
Answer:
Correct Answer: D
Solution:
[d] The axial magnification $ \delta v=-\frac{v^{2}}{u^{2}}\frac{dt}{dt} $
$ ={{( \frac{f}{u-f} )}^{2}}\ell . $
