What's the difference between electricity and electronics?
If you've read our article about electricity,
you'll know it's a kind of energya very
versatile kind of energy that we can make in all sorts of ways and use
in many more. Electricity is all about making electromagnetic energy
flow around a circuit so that it will drive something like an electric motor or a heating element,
powering appliances such as electric cars,
kettles, toasters, and
Generally, electrical appliances need a great deal of energy to make
them work so they use quite large (and often quite dangerous) electric
currents. The 2500-watt heating element inside an electric kettle
operates on a current of about 10 amps. By contrast, electronic components use currents
likely to be measured in fractions of milliamps (which are thousandths of amps). In other words, a typical
electric appliance is likely to be using currents tens, hundreds, or thousands
of times bigger than a typical electronic one.
Electronics is a much more subtle kind of electricity in which tiny
electric currents (and, in theory, single electrons) are carefully
directed around much more complex circuits to process signals (such as
those that carry radio and
television programs) or store and process
information. Think of something like a microwave
oven and it's easy to see the difference between ordinary
electricity and electronics. In a microwave, electricity provides the
power that generates high-energy waves that cook your food; electronics
controls the electrical circuit that does the cooking.
Artwork: Microwave ovens are powered by electric cables (gray) that plug into the wall.
The cables supply electricity that powers high-current electrical circuits and low-current electronic ones.
The high-current electrical circuits power the magnetron (blue), the device that makes the waves that cook your food,
and rotate the turntable. The low-current electronic circuits (red) control these high-powered circuits,
and things like the numeric display unit.
Analog and digital electronics
There are two very different ways of storing informationknown as
analog and digital. It sounds like quite an abstract idea, but it's
really very simple. Suppose you take an old-fashioned photograph of
someone with a film camera. The camera captures light streaming in
through the shutter at the front as a pattern of light
and dark areas on chemically treated plastic.
The scene you're
photographing is converted into a kind of instant, chemical paintingan
"analogy" of what you're looking at. That's why we say this is an analog
way of storing information. But if you take a photograph of exactly the
same scene with a digital camera,
the camera stores a very different record. Instead of saving a
recognizable pattern of light and dark, it converts the light and dark
areas into numbers and stores those instead. Storing a numerical, coded
version of something is known as digital.
Photo: Digital technology: Large digital clocks
like this are quick and easy for runners to read. Photo by Jhi L. Scott
courtesy of US Navy.
Electronic equipment generally works on information in either analog
or digital format. In an old-fashioned transistor radio,
broadcast signals enter the radio's circuitry via the antenna sticking
out of the case. These are analog signals: they are radio waves,
traveling through the air from a distant radio transmitter, that
up and down in a pattern that corresponds exactly to the words and
music they carry. So loud rock music means bigger signals than quiet
classical music. The radio keeps the signals in analog form as it
receives them, boosts them, and turns them back into sounds you can
hear. But in a modern digital radio,
things happen in a different way. First, the signals travel in digital
formatas coded numbers. When they arrive at your radio, the numbers
are converted back into sound signals. It's a very different way of
processing information and it has both advantages and disadvantages.
Generally, most modern forms of electronic equipment (including computers, cell
phones, digital cameras, digital radios,
hearing aids, and televisions) use