2.06 Voltage Drop.

There are two types of potential difference.

  1. An electro-motive force (e.m.f.).

    An e.m.f increases the electrical potential of the electrons. e.g. The voltage across a battery, is due to the e.m.f. increasing the potential of the electrons, as it transfers them between its terminals. The electrons leaving the negative terminal, have a higher potential than the electrons arriving at the positive terminal.

  2. A potential drop (p.d.) (or voltage drop (v.d.)).

    A voltage drop occurs across a component that reduces the electrical potential of the electrons as they pass through it. e.g. A resistor converts electrical energy to heat and therefore lowers the potential of the electrons passing through it. A voltage drop occurs across a resistor, because the electrons flowing out of the resistor, have a lower potential than those flowing into it.
Electrical potential