The nichrome alloy does not oxidize when heated. Iron wire would rust very quickly at the temperatures seen in a toaster. You would drop a piece of bread into the slot. You would then plug in the toaster and watch the bread. When the bread became dark enough, you would unplug the toaster. Then you would tip the toaster upside down to get the toast out! A spring-loaded tray pops the toast out.
This keeps you from having to turn the toaster upside down. A timer turns the toaster off automatically and at the same time releases the tray so the toast pops up. By: Sharita Sykes. For generations, the simple toaster has warmed and browned everything from bread to waffles.
This toaster isn't as simple as it may seem, though. It uses electronic components like capacitors, microchips and even an electromagnet.
To make toast, the first step is placing the bread in one of the trays on the toaster. Once the bread is in place, the next step is pressing the lever. The lever, shown here in red, connects to a metal plate.
A wedge is attached to the metal plate. Go to the next image to see why the wedge is important. The wedge forces strips of metal to touch contacts on a printed circuit board PCB. I failed to get pure enough iron in this way, though if I'd tried a few more times and refined my technique and knowledge of the process I probably would've managed in the end. Instead I found a patent about industrial smelting of Iron ores using microwave energy.
Microwaves, as we all know, are just so much more convenient - and so I tried to replicate the industrial process outlined in the patent using a domestic microwave. After some not-so-careful experimentation which necessitated another microwave, followed by some careful experimentation, I got the timing and ingredients right and made a blob of iron about as big as a 10p coin.
The practical aspects of the project are rather a lot of fun. They also serve as a vehicle through which theoretical issues can be raised and investigated. Commercial extraction and processing of the necessary materials happens on a scale that is difficult to resolve into the domestic toaster. The contrast in scale between between consumer products we use in the home and the industry that produces them is I think absurd — massive industrial activity devoted to making objects which enable us, the consumer, to toast bread more efficiently.
All the energy can't transfer down the nichrome wire, so instead its energy becomes heat. This means the wire gets very, very hot! The same kinds of heating elements are used in combination with a fan in household hair dryers. The heating elements heat up everything around them, including the bread. If the bread is close to the heating element for the right amount of time, it turns a light brown color and turns into toast.
If it is heated too long, the toast will turn black and begin to smoke. Toasters are generally built so that they stop on their own, to prevent this from happening. A pop up toaster causes the toast to "pop" up when it stops. The slots in the top of it hold the bread. When the bread is first added, a cage at the bottom of the slot holds it up, partway out of its slot. At first, the heating elements are not hot, because no electrical current is flowing through them.
The black lever on the right can be pushed down, which lowers the bread all the way in, so that it is very near the heating elements. Two other important things happen as the lever is pushed down. First, with the lever pushed down, the toaster allows electricity to flow through the heating elements, which causes the bread to start toasting.
0コメント