ng-rooms large or put them close
together.

If we make the plates of a condenser larger, keeping the separation
between them the same, it means more space in the waiting-rooms and
hence less crowding. You know that the more crowded the electrons become
the more they push back against any other electron which some battery is
trying to force into their waiting-room, that is the higher the e. m. f.
of the condenser.

The other way to get a larger capacity is to bring the plates closer
together, that is to shorten the gap. Look at it this way: The closer
the plates are together the nearer home the electrons are. Their home is
only just across a little gap; they can almost see the electronic games
going on around the nuclei they left. They forget the long round-about
journey they took to get to this new waiting-room and they crowd over to
one side of this room to get just as close as they can to their old
homes. That's why it's always easier, and takes less voltage, to get the
same number of electrons moved from one plate to the other of a
condenser which has only a small space between plates. It takes less
voltage and that means that the condenser has a smaller e. m. f. for the
same number of electrons. It also means that before the e. m. f. rises
to one volt we can get more electrons moved around if the plates are
close together. And that means larger capacity.

There is one thing to remember in all this: It doesn't make any
difference how thick the plates are. It all depends upon how much
surface they have and how close together they are. Most of the electrons
in the plate which is being made negative are way over on the side
toward their old homes, that is, toward the plate which is being made
positive. And most of the homes, that is, atoms which have lost
electrons, are on the side of the positive plate which is next to the
gap. That's why I said the electrons could almost see their old homes.

[Illustration: Fig 41]

All this leads to two very simple rules for building condensers. If you
have a condenser with too small a capacity and want one, say, twice as
large, you can either use twice as large plates or bring the plates you
already have twice as close together; that is, make the gap half as
large. Generally, of course, the gap is pretty well fixed. For example,
if we make a condenser by using two pieces of metal and separating them
by a sheet of mica we don't want the job of splitting the mica. So we
increase