Year 1 Sem 1/LC Optics and Waves/Lecture 13
Sign Rules
We have the mirror equation:
$$\frac{1}{s} + \frac{1}{s^\prime} = \frac{1}{f}$$
The numerical values of $s$ and $s^\prime$ give us the distance, but the position of the formed image is determined by their signs.
Mirrors
The image formed by a mirror is:
- Virtual, as we effectively see it appears as being behind the mirror, where there is no real light.
- Erect, as there is no inversion (if you stand in front of a mirror, you see your body in the same top-to-bottom orientation as real life).
- Reversed, as if you look in a mirror your body faces you, and you see your face, not your back.
Angled Mirrors
If we have a pair of hinged mirrors, changing the angle between them changes the way that the image is produced. Crucially, it changes how many images of the object we see:
