2.3 Voltage
When charges are detached from one body and transferred to another, a
potential difference or voltage results between them. A familiar example is
the voltage that develops when you walk across a carpet. Voltages in excess
of ten thousand volts can be created in this way. (We will define the volt rigorously
very shortly.) This voltage is due entirely to the separation of positive
and negative charges.
Figure 2–7 illustrates another example. During electrical storms, electrons
in thunderclouds are stripped from their parent atoms by the forces of
turbulence and carried to the bottom of the cloud, leaving a deficiency of
electrons (positive charge) at the top and an excess (negative charge) at the
bottom. The force of repulsion then drives electrons away beneath the cloud,
leaving the ground positively charged. Hundreds of millions of volts are created
in this way. (This is what causes the air to break down and a lightning
discharge to occur.)