An electric toaster is not complex machine, but
there's more going on in that little slotted box then the average
person probably thinks. The basic principle (bread goes into slot,
slot gets hot, toast pops out) is easy enough to follow, but what's
really going on beneath the toaster cover is a bit more complex.
Here's how it works. A rider in the slot holds
the bread. When the handle is depressed the rider carries the bread
down into the slot. Grates close around the bread to center it and
an electromagnet holds the rider down until the timer goes off.
At the same time a pair of contacts are forced
together, sending current through nichrome wire that is crisscrossed
over a mica sheet. This causes the highly resistant nichrome to
produce a great deal of heat very quickly. The bread is toasted
(i.e. lightly charred) by infrared radiation produced by these heated
coils.
When the timer, i.e. the toaster's Darkness Setting,
goes off the electromagnet is deactivated, causing the spring-loaded
tray to pop up and disengage the contacts, which in turn breaks
the circuit and stops the current from flowing through the heating
element. |
