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The Inside Scoop of
the Toaster Oven
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Alexa Fox and George Bonnewell
History
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Earliest toaster
– Manual toaster with no moving parts
• Bread was just placed on the rack and by
turning the rack, the bread got toasted.
(pictured on left)
Semi-Automatic toaster
– Includes a bell that lets you know when the
toast is ready
– Thermostatic switch to control the
temperature
Today’s toasters
– Automatic toasters
• Electric current heats the bread
• Timing device to control toast process
How a Toaster works
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Toasters use the simple idea of resistance to provide heat, do work, and
prepare the desired finished product. From the time the toaster is
plugged in, to its final spring loaded pop, a toasters mechanisms can be
clearly explained by any Physics 001 student.
In order to provide heat, toasters usually use a material like Nichrome
(comprised of nickel and chromium) and weave it in bands throughout the
inside of the toaster. (pictures on left) This material is of high
resistance, and is generally an alloy.
On an atomic scale, when electricity passes through an object with high
resistance the particles collide more often, resulting in the loss of
kinetic energy, or transfer of kinetic energy to heat. Because the
collisions make the atoms passing through the material vibrate, they
become hotter than the surrounding medium (air in this case) and the
heat is transferred to the food placed inside the toaster.
The change in kinetic energy equals the work done, which equals 1/2mv^2
– 1/2mv^2 (final – initial).
This example stays true to the Law of Conservation of Energy, because
energy is neither being destroyed or created, but is kinetic energy being
transferred into heat which we learned about in class this semester.
How a toaster works
continued
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Although you can use many different alloys to create thermal
energy and heat your toast, one still encounters the problem of
getting the toast out of the toaster. This is where resistors
and capacitors come into play, which were discussed in class
this semester.
From the moment the toast is pressed down into the toaster, a
small electro-magnet holds the handle of the toaster down.
(This is where the spring loaded jump comes from at the end)
After that, a small circuit board in the toaster starts charging
a capacitor. In simple terms, a capacitor stores a charge in a
circuit. This capacitor is paired with a resistor, just like the
ones demonstrated online while in class. Once the voltage in
the capacitor reaches a designated level, the electro-magnet is
turned off and the toast pops up.
To determine the darkness of ones toast, the dial on the
outside of the toaster changes the resistance on the resistor
that is paired with the capacitor. Changing the resistance in
the capacitor will affect how long it takes the capacitor to
charge, and how long it takes to get to the designated voltage
release level for the toast. Because Voltage = Current x
Resistance, less resistance or more resistance will determine
how long it takes for the voltage to build up. (in the toasters
case) Voltage is also another topic that was discussed in class.
New Insight
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We now know how our bread and bagel are toasted every morning.
Something that seems so easy is actually so complex and takes a lot
of work. Our job is just to put the bread in the toaster and the
toaster, this little machine, does the rest of the work. Our bread
would be cold every morning without this fabulous invention. Within
the toaster, electricity is flowing through the metal coils and
kinetic energy turns into thermal energy. The thermal energy is
what allows your toast to turn brown and warm. Heat is not just
created from a fire. Heat can also be created from electricity, like
in a toaster.
From start to finish a toaster combines the principles of electricity
and magnetism, as well as the principles of work, and the transfer
of energy to get the job done. The toaster executes basic physics
principles, yet if one used copper, a low resistance material
generally used for wiring, this process would not have worked.
Understanding these basic principles plays a large role in the ability
for a toaster to provide its simple service.
Works Cited
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(2012). Physics and how machines work. Burn an Energy Journal ,
Retrieved from http://burnanenergyjournal.com/energyscience/physics/
Brain, M. (n.d.). How toasters and capacitors work. Retrieved from
http://home.howstuffworks.com/toaster2.htm
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(1998 ). Toasters: The inside story. Hotwire, Retrieved from
http://www.toaster.org/works.html