Measuring Resistance
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To begin, make sure no current is running through the circuit or
component you want to test. Switch it off, unplug it from the wall, and remove
any batteries.
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Remember that you'll be testing the resistance of the entire circuit. If
you want to test an individual component such as a resistor, test it by
itself—not with it soldered in place!
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Plug the black probe into the COM port on your multimeter.
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Plug the red probe into the VΩmA port.
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Switch on your multimeter, and set the dial to resistance mode.
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Resistance is measured in ohms, indicated by the Ω symbol.
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Most multimeter are not auto ranging, meaning you will need to set the
correct range for the resistance you expect to measure. If you're not sure,
start with the highest setting.
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Place one probe at each end of the circuit or component you want to
test.
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It doesn't matter which probe goes where; resistance is non-directional.
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If your multimeter reads close to zero, the range is set too high for a
good measurement. Turn the dial to a lower setting.
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If you set the range too low, the multimeter simply reads 1 or OL,
indicating that it is overloaded or out of range. This won't hurt the
multimeter, but we need to set the dial to a higher range.
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The other possibility is that the circuit or component you are testing
doesn't have continuity—that is, it has infinite resistance. A non-continuous circuit will
always read 1 or OL on a resistance test.
With the multimeter set to a usable range, we get a
reading of 1.04k ohms.
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