2.06 Voltage Drop.
There are two types of potential difference.
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.
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.