The Inside Scoop of the Toaster Oven

1. The Inside Scoop of the Toaster Oven Alexa Fox and George Bonnewell

2. History • 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

3. How a Toaster works • 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.

4. How a toaster works continued • 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.

5. New Insight • 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.

6. Works Cited • (2012). Physics and how machines work. Burn an Energy Journal , Retrieved from http://burnanenergyjournal.com/energy-science/physics/ • Brain, M. (n.d.). How toasters and capacitors work. Retrieved from http://home.howstuffworks.com/toaster2.htm • (1998 ). Toasters: The inside story. Hotwire, Retrieved from http://www.toaster.org/works.html