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Tim Williams
 
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Default Turn Your Power Supply into an Ohmmeter - It's Free!

"Ratch" wrote in message
news:%RxSa.92479$GL4.26156@rwcrnsc53...
Wait a minute, if L&M say that Ohm's law is V=IR (which it is not),

and
materials that obey Ohm's law are "ohmic", then by L&M's definition, all
materials are ohmic because the resistance formula V=IR is always correct
for all materials. How is a material defined as "nonohmic"? Ratch


Ohm's law. Sounds to me like it applies when R represents an ohmic
material.
*duh*

And it still applies. Let's say we forward bias a diode. So, we put 20mA
on it and measure .7V. V=IR = .7 = .02R, divide by .02 and we find the
diode is 35 ohms. Of course, since it's a nearly constant voltage whatever
the current flowing, the resistance drops as current rises, making it a
rather nonohmic component, and it's a more or less pointless calculation.
But it still applies: given the current doesn't change from those 20mA,
it could be replaced by a 35 ohm resistor and the same voltage drop is
produced.

Tim