What Is Electricity? | 1945 | Educational Film


Electricity is one of our most faithful
servants it gives us light It starts our cars
has unlimited aviation circle lobe with entertainment it cooks,
and refrigerates our food these represent few of the innumerable
applications of electricity electricity at work but what is electricity and
where does it come from to answer these questions let’s look in on the world of
electrons the entire universe is composed of matter a basic concept of
the structure of matter is essential for the understanding of electricity because
the very force that holds matter together has an electrical nature there
are many different substances each a combination of some of the ninety-two
known chemical elements just as yeast flour salt sugar and shortening are the
ingredients used in making bread so are the 92 elements the ingredients
of all matter and if one of these elements is reduced
to its purest final form it’s smallest unit would be an atom no
one has ever seen inside an atom however we think of it as a system of electrons
circulating around a heavy nucleus at almost inconceivable speeds in order to
explain the principles with which we are concerned in this story let’s assume
that we can stop the action within the atom and further let’s acknowledge that
this is a symbol representing the atom and not an attempt to show it as it
actually is it is impossible to show the correct relative proportions of an atom
on this screen for example if an atom could be as large as the United States
one of its electrons would be only about 100 feet across
therefore to tell our story we must resort to a symbol then we can
think of the atomists being a group of relatively light small particles
arranged around a heavy nucleus these are particles of electric energy the
lighter ones the electrons are negative electric charges and the heavier one the
nucleus carries positive charges normally a state of balance is
maintained within the atom by a positive charge in the nucleus equal to the total
negative charge of the electrons and when the atom contains its normal number
of electrons it is said to be in electrical balance to be in a neutral
electrical condition it is possible however to disturb this normal balance
whereupon the unbalanced atom assumes an electric charge too many electrons will
produce a negative charge to fuel will throw the balance out of the
positive sign in order to visualize better the effect of this let’s
introduce a color code in which the positive charge or an absence of
electrons is represented with red and a negative charge a predominance of
electrons with blue then an object that is in electrical balance will be purple
an equal part of each of the positive and negative charges we have been
concerned so far with the electrons within individual atoms now let’s see
what happens when two or more neutral atoms come together the outside
electrons will no longer move exclusively within their original atoms
but will circulate about both atoms at once and if we bring many such atoms
close together as in a piece of metal then many electrons detach themselves
from their original atoms and move freely throughout the metal as long as
the metal has its normal number of electrons it is electrically neutral but
like an individual atom it can lose some of its electrons and become positively
charged or it can pick up more than its normal number of electrons to become
negatively charged the electrons always try to get from a negatively charged
body to one that is positively charged in relation to it and if are brought
together the electrons will flow from one to the other until both objects are
equally charged the establishment of unbalanced charges in matter is in all
instances the principle of the generation of electricity to illustrate
further this principle let’s analyze the action within a cell a simple source of
electric energy a piece of zinc is suspended in a suitable container its
atoms are neutral until a chemical solution
and then some of the zinc atoms go into the solution leaving a few of their
electrons behind in the metal the zinc becomes strongly negatively charged now
up to be electrically neutral copper is put in a chemical solution in another
container the copper will become very weakly negative since the copper has a
smaller negative arch it is positive with respect to the zinc and if the two
metals are connected the electrons will surge from the zinc to the copper and
the charges will become equalized this momentary current has little practical
value however if we now connect the solutions the charges in the solutions
will become equalized and the metals or terminals will be charged we will then
have an unbalanced condition of the electrons in the metals capable of
producing a continuous flow of useful electric current all of the work
performed by electricity requires a flow of current so let’s see what principles
are involved when current flows there are three related to flow of electricity
they are pressure or voltage current intensity and resistance first let us
consider pressure with nature always trying to maintain an electrical balance
there is a tendency for any negatively charged object to throw off or repel in
success of electrons and for a positively charged object to attract
electrons this urge to maintain an electrical balance is potential electric
energy and since this potential energy is a repelling and attracting urge
caused by opposite charges its force or pressure is equal to the difference
in the charges it is called the difference in potential or potential
difference the unit of pressure or potential difference is the vote the
voltage then is always the potential difference at the negative and positive
terminals of the source of the electric energy it represents the difference
between the number of extra electrons at the two terminals and when a suitable
path is provided the potential difference causes the electrons or
current to flow from one terminal through the conductor to the other
terminal to explain how this works let’s review the action of the atoms and their
electrons in a piece of metal where we saw forms of electrons moving freely in
all directions about the atoms substances in which this
takes place are good conductors of electricity if an outside electric
pressure or voltage is applied to a conductor the electrons will move
predominantly in one direction the effect is that electrons move from the
negative to the positive terminal this is the electric current the unit of
electric current is the ampere 1m now hold on to your hat sixth billion three
hundred million billion electrons passing any given point in one second current or amperage then is the number
of electrons that pass a given point in a given time and now the third factor resistance this
factor is controlled by the nature of the material through which the electrons
flow again going back to the motion of electrons in a metal we said that they
moved freely about and among the atoms however even in the best of conductors
some of the electrons collide with the atoms tending to retard the movement of
the electrons this is the cause of electric resistance collisions are more
probable in some metals than in others therefore different metals offer
different degrees of resistance to the flow of electrons for example copper has
low resistance it permits the electrons to flow freely with few collisions and
is therefore a good conductor iron offers more resistance than copper
collisions where the atoms are more frequent in some substances no electrons
are free to move around as in the metal all of the electrons stay with their
atoms so that no current can flow these substances are the insulators glass
porcelain rubber and many others the collisions that the electrons have with
the atoms set the atoms into more violent vibration this makes the metal
hotter if there are enough of these collisions the metal will radiate heat
and light heat and light from electrical sources then can be obtained as the
result of resistance in some metals the unit of resistance is the old its value
is best understood when its relation to the other factors is explained a
pressure of one volt produces a current of one ampere through
a resistance of 1 ohm whatever the source or the magnitude of electric
energy these factors always have the same relation to each other so in
order to supply our great demands for electric power we must have facilities
for generating great currents at sufficient pressures to overcome the
resistance of the lines as well as to do the work power for industry transportation and light as well as for
many other conveniences we use in our daily lives our almost a belief or mieze
amounts of work are the electromagnetic generators in order to explain the
manner in which electricity is produced by electromagnetic generators and used
in most electrical machinery let’s have a look at magnets and magnetic fields the earth itself is a magnet so are the
tiny electrons all of the electrons in any object are tiny magnets when a
predominant number of these tiny magnets point in one direction we have an
extremely small magnetized block called a magnetic domain magnetic material that
is material capable of being magnetized is made up of such domains pointing in
all directions when these domains all point in the same direction we have a
magnet in some materials such as copper a tiny magnets of the electrons never
line up these materials are non-magnetic cannot be magnetized every magnet has a
magnetic field magnets may be made in various shapes to provide convenient and
strong fields to understand how a magnetic field is useful in the
generation or application of electricity let’s go back to the electron mister
electron and watch him move across the magnetic field will you do it again bud
now notice as he enters the magnetic field
he’s deflected from his original course his deflection depends upon his velocity now as we have previously shown
conductors have many free electrons and if a conductor is moved across a
magnetic field the mechanical action causes the electrons in the wire to be
deflected just as we saw mister electron deflected this in effect establishes a
neck and a positive charge at the ends of the
conductor we now have two charged terminals capable of producing a
continuous flow of electric current just as we had in the cell
this is accomplished in practice by providing a means of continuing the
movement of a conductor within a magnetic field in all electromagnetic
generators regardless of size the same principle is used to generate
electricity the deflection of electrons in a conductor moving across a magnetic
field thus a magnetic fields and forces are also used in making an electric
current perform useful mechanical work remember that an electron moving across
a magnetic field is deflected if the electron were moving in a wire as when
electric current flows the deflection of the electron would cause it to push
against the wire tending to move the wire billions upon billions of these
tiny pushes combine to provide the force the stronger the current or the greater
number of electrons the greater the force moving the wire these forces on
current-carrying wires in magnetic fields furnish the power for all
electric motors from the simplest to the most complex from the smallest to the
largest electric motors the principle is the same the deflection of electrons
flowing in current-carrying wires by magnetic fields in fact interaction
between the magnetic fields and the electrons is the basis of all in
devices and now we may summarize that the billions and billions of atoms of
which the universe is built are composed of positive and negative electric
charges that these charges are normally balanced
in matter that by unbalancing these charges electric energy is made
available that the urge of nature to restore this balance creates electric
pressure and that the response this urge the action of the restoration of the
balance is a flow of electric current the flow of electric current then is
simply movement of electrons away from objects that have acquired a negative
charge two objects whose charge is relatively positive it’s this principle
that has made possible the countless electric devices which contribute to the
comfort and fulfillment of richer and happier living today devices which will
expand that through unlimited horizons in the future devices whose operation is
dependent upon nature’s design format Dometic that matter itself shall always
seek a state of millech Trickle balance

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