There are many different elements of
physics that relate directly to the operation
of Edison’s favorite invention, the Phonograph.From the
mechanics of the lever,
to the transferring of speech to foil, physics play a
part in the success of the
Phonograph.
The Handle and Flywheel
A hand crank controls the rotation of
the phonograph’s mandrel.Amazingly, the
phonograph does not rely on electricity but manpower.In order to
get a clean
recording, the handle must be cranked at a steady
angular velocity.This
requires
the user to drive the motion at a constant velocity but
this can be a challenging
task for a person to undertake.For this
reason, Edison included a flywheel.The
flywheel has a high moment of inertia and resists
changes in rotational speed.
Once torque is applied, the flywheel will continue
rotating at a relatively constant
velocity.
The
Horn
The horn is used both in recording
and playing back sounds.It is important that
the horn is made of a material that will not trap or
distort the sound when
recording.For
this reason, a rigid material is ideal in having sound
bounce off the
walls of the horn and travel to the mouthpiece.The same can
be said in reverse as
the mouthpiece projects recordings through the horn.Understanding
the acoustics
of the phonograph is a difficult undertaking.To get a more
in depth take on the
phonograph and how the composition of the horn affects
sound quality click this
link. http://www.texasacoustics.org/images/stories/JASMAN13242173_1.pdf
Mouthpiece
and Foil
The interaction between the
mouthpiece and foil is an integral part of creating a
recording. Energy
is transferred from the speaker’s voice down the horn,
through
the mouthpiece, and onto the foil wrapped mandrel.However, all
the energy does
not make it down to the foil and some goes to the
environment.A
fraction of the
sound waves created by speech becomes trapped in the
horn, vibrating the walls
instead of getting to the mouthpiece.In addition,
the interaction between needle
of the mouthpiece and the foil is imperfect.There is
friction between the two
objects so even more of the energy is turn into thermal
energy.Similar
transfers
of energies occur when the phonographs plays sound back
through the horn.
Conclusion
As he tinkered with his invention,
many properties changed.Edison upgraded the
foil to wax and took measures to create uniform motion
of the rotating mandrel.
Although the phonograph underwent many changes
throughout it’s lifetime,
Edison successfully created a revolutionary machine that
could transfer acoustic
vibrations onto a playable medium.His invention
paved the way for similar
inventions that used this concept such as vinyl records.
Edison’s most
influence and famous invention is the light bulb.Without this
invention, people would be limited to only doing work
when the sun permitted.
Not only did incandescent lighting improve
productivity of mankind as a whole
but it also offered a safer alternative to burning
candles or fossil fuels.However,
much like any good invention, there is quite a bit of
physics involved in the
success of Edison’s invention.
How Does It Work?
While Edison was not
the first to make the light bulb, he successfully
commercialized the light by increasing the amount of
hours the filament will burn.
The first light bulb made by Edison had a carbon
filament unlike today’s
incandescent lights that are made from tungsten.By running
an electric current
though the filament, both heat and light are emitted.Although
incandescent bulbs
are an incredible form of lighting, another more
efficient source of light is
fluorescent bulbs.Unlike incandescent lights, fluorescent lights
excite the
atoms of gas molecules instead of heating a solid
filament.As
a result, less
energy is expended to heat and more is turned into
light.However,
fluorescent
lights are difficult to dispose because they contain
harmful elements like mercury.
Filament and Bulb
The filament in a
light is the most important part in creating a
glow. Edison tested
over 6,000 different materials before he tried using
carbonized thread as a
filament. In order to be successful, the
filament must have a high melting point
and resist the flow of electricity. These traits
ensure that the filament heats up
enough to glow and remains solid when it is hot.
One reason Edison was
successful with his invention was the lifespan of his
bulbs. He evacuate the glass
casing of his lights, leaving no oxygen. This
process kept the carbon from
oxidizing when it was
heated. Similar methods are used in today's
incandescent
lights. In order to prevent oxidation, many
lights are filled with argon, an inert
gas that slows filament evaporation. Small
amounts of nitrogen are also used in
bulbs to prevent arcing from occurring.
Conclusion
While the efficiency and quality of incandescent
lights has grown exponentially
since they were invented, none of these strides would
have been possible without
the work of Edison and many other scientists. In
order to truly understand how
lights work, an understanding of electricity is
essential. To get a better grasp on
the concept of electricity, click this link,
