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Touching
against the crystal was something called a cat's whisker, a
tiny metal wire often composed of steel or even gold. By
moving it, the radio user tried to find one of the so-called
"magic spots." The reason for this name was that only small
areas on the crystal would make the radio function - just
like magic. When the whisker was positioned over a "magic
spot" an electrical signal travelled down the metal wire and
through the crystal. When this happened you could hear the
music being transmitted from the radio station. This was an
example of a phenomenon called rectification. Rectification
means that an electrical current is only allowed to pass in
one direction and not in the other. In the crystal radio the
cat's whisker and the crystal worked as a
rectifier. |
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