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How does a light meter work?
We can think of light as coming in tiny packets called photons. For
normal levels of light, the photons come in so quickly that we usually
don't try to detect each one individually. Instead we build a device
(called a light meter) whose output tells us the rate at which photons
are hitting the device, often referred to as "intensity".
this, we often use a special material called a semiconductor.
Semiconductors come in many types, and are used to make everything from
computer chips to the circuits in your TV set. The type of
semiconductor used in light meters is specially made so that when a
photon hits it a tiny bit of electricity flows for a very very short
time. Since there are a lot of photons hitting the semiconductor, the
tiny bits of electrical current from each photon add together to give a
steady current that is big enough that we can measure it with an
ordinary current meter. If more light hits the semiconductor, more
current will flow and the meter will read a bigger value. This means
that people looking at the meter (like you) will know that the
intensity of light just went up.
(published on 10/22/2007)
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