97Chapter 11Electricity and Magnetism
A Newtonian description of nature requires an understanding of the
basic forces that operate between the various constituents of the universe.
So far, the only force we have discussed in any detail is the gravitational
force. We shall now turn our attention to the electric and magnetic
forces, which, we will soon discover, are intimately connected to each
other and are referred to collectively as the electromagnetic interaction.
The electromagnetic interaction plays a major role in determining both
the structure of matter and the general interactions of matter as we
discussed in the last chapter. The reason for this is, that of the three
major constituents of gross matter, the proton, the neutron and the
electron, two of them, the electron and proton, are charged and hence,
exert an electric force whereas all three possess magnetic moments and
hence, exert magnetic forces. As a result of this the internal structure
of atoms and molecules, as our future studies will reveal, are governed
by the electromagnetic interaction. For example, the negatively charged
electrons of an atom are held in their orbits about the positively charged
nucleus by the electric force. Not only are the forces inside the atom and
molecule electromagnetic, but also the forces between atoms and
molecules are electromagnetic. Molecular bonds are responsible for
the structure of gross matter. Hence, the resistance one feels when one
tries to penetrate solid matter is electromagnetic as is the force exerted
by a coiled spring. The forces produced by chemical action are also
electromagnetic since all chemical reactions are governed by the electric
properties of an atom’s outer electrons. The production of light, as we
will soon see, is also a result of the electromagnetic interaction.
In addition to the natural phenomena referred to, we encounter the
effects of the electromagnetic interaction in a steadily increasing number
of devices and machines invented by humans for their convenience and