BASIC ELECTRONICS - OD1633 - LESSON 1/TASK 1
particle having a single positive charge; a group of protons produce a
positive electrical charge. An electron is a basic particle having a single
negative charge; therefore, a group of electrons produce a negative
electrical charge. A neutron is a basic particle having no charge; a group
of neutrons, therefore, would have no charge.
First, let us examine the arrangement of atoms in some elements, starting
with the simplest of all, hydrogen.
The atom of hydrogen consists of one
proton, around which is circling one electron (figure 1 on the following
page). There is an attraction between the two particles, because negative
and positive electrical charges always attract each other.
Opposing the
attraction between the two particles, and thus preventing the electron from
moving into the proton, is the centrifugal force on the electron, caused by
its circular path around the proton.
This is the same sort of balance
achieved when a ball tied to a string is whirled in a circle in the air.
The centrifugal force exerted tries to move the ball out of its circular
path, and is balanced by the string (which can be defined as the attractive
force). If the string should break, the centrifugal force would cause the
ball to fly away. This is what happens at times with atoms. The attractive
force between the electron and proton is sometimes not great enough to hold
the electron in its circular path, and the electron gets away.
A slightly more complex atom, shown in figure 1, is the atom of helium.
Notice that there are two protons in the center.
Because there is an
additional proton in the center, or nucleus, of the atom, an electron must
be added so as to keep the atom in electrical balance.
Notice also that
there are additional particles in the nucleus; these are called neutrons.
Neutrons overcome the tendency of the two protons to move apart from each
other.
Just as unlike electrical charges attract, so do like electrical
charges repel.
Electrons repel electrons.
Protons repel protons, except
when neutrons are present. Though neutrons have no electrical charge, they
cancel out repelling forces between protons in an atomic nucleus and thus
hold the nucleus together.
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