Editing Category:Common Issues (section)

==== Resistance Mode (Ohms) ====
This mode injects a current through the two probes (small, typically 1{{--}}10{{nbsp}}mA) and measures the voltage developed across the load. for resistive loads (like resistors!) this follows Ohm's law: V = IR. Because the DMM is good at measuring voltage, and we know the output current (or at least the meter does) this gives us the resistance of the component under testing. Of course, there are some traps here that you should know about before you are complaining that your measurements don't work correctly. First, because it is outputting a current, this mode will tend to charge up capacitors. This is why sometimes when you are trying to do a reading, the value will drift up as the capacitor soaks up the current and develops a larger voltage across it. Another side product that can happen from this mode is that the current being injected into the circuit can leak into diode junctions and (very slightly) turn on diodes/transistors, causing the voltage to discharge away. So, if you want to take good resistance measurements, just keep these things in mind and try to probe mindfully to make the most of your measurements. The most accurate way to make resistance measurements is to remove the component and test it out of circuit.