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= (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=(-) (50 cm)/(80 cm)=-0.63`