How to Measure Volts, Amps and Ohms with a Digital Multimeter

A digital multimeter is a versatile tool that integrates three testing devices - a voltmeter, ammeter, and ohmmeter - into one easy-to-use handheld unit.  This article presents a simple and straightforward guide on how to use each of the testing functions contained in a multimeter.

Measure Volts with the Voltmeter

Voltage, which is essentially the electrical potential of a device,  is measured with a voltmeter.  

To use the voltmeter function to measure DC volts, turn the function switch to “V=” setting.  Connect the black and red leads to the multimeter.   The red lead you will connect to the red input terminal which is labeled  “V&#937.”   The black lead you need to connect to the terminal that is labeled “COM,” which stands for “common terminal.”  

Once the leads are connected, you are ready to measure the voltage of a circuit.  Attach the red lead to the terminal with the higher potential; attach the black lead to the terminal with the lower potential.

Measure Amps with the Ammeter

Amps are the amount of electrical current that flows in an electric circuit.  For measuring amps with the ammeter function, you will need to connect the leads differently than you did with the voltmeter.   The first step is to set the function switch to the “A=” point on the dial.  Next, connect the red lead to the terminal that says “300mA,” and connect the black lead to the terminal labeled “COM.”  

When you've attached the leads as described, you can now connect the meter in series to the device you wish to measure.   Just open up the circuit and insert the meter between the open points and you can measure the amps.  You will see the results as milliamps, as you are using the 300mA terminal.

Measure Ohms with the Ohmmeter

Ohms are the units that indicate how much electrical resistance is in a circuit.  To measure ohms, you will use the ohmmeter function of your digital multimeter.    The first thing you must do is to disconnect the power and wiring from the circuit you wish to measure.   When all is disconnected, rotate the function switch to “&#937.”    Attach the red lead to the “V&#937” terminal.   Attach the black lead to the “COM” terminal.  

Your display should have a readout of “OL,” which indicates there is an overload.    Finally, all you need to do now is connect the leads to the circuit you wish to measure to get a readout of the ohms.    

In a nutshell, we have just seen how to use the voltmeter, ammeter, and ohmmeter functions of a digital multimeter.   By having three essential electrical measurement functions neatly contained in one hand-held tool, you don't need to carry around three separate devices in your tool bag.  Be sure to turn off your device when you are done to conserve you battery for the next time you use it.

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