Question

A 80-cm-wide object seen through an optical device appears inverted and 50 cm wide. What is the magnification of the optical device?
A. 1.3
B. 0.63
C. -0.63
D. 2.5
E. -1.3

Answer 1

The magnification is the ratio between the size of the image $h_i$ and the size of the original object $h_o$:
$M= \frac{h_i}{h_o}$
The sign of the magnification contains another piece of information: if it's positive, then the image is upright, if it's negative, the image is inverted. In our problem, the image is inverted, so the magnification will have a negative sign, and it will be
$M=(-) \frac{50 cm}{80 cm}=-0.63$