Final answer:
The teeth of a comb become negatively charged due to the transfer of excess electrons from a rubber belt, illustrating static electricity through triboelectric charging.
Step-by-step explanation:
When discussing the teeth of a comb in a physical context, you are likely referring to an electrostatic phenomenon. When a rubber belt is in contact with the teeth of a comb, there is a transfer of electrons. This is due to the process of triboelectric charging, where differing materials exchange electrons upon contact. If the comb has the tendency to acquire excess electrons, it will become negatively charged. This is a classic example of static electricity, where the electron transfer leads to an electrostatic charge being built up on the object.