How to Measure DC Voltage with a Digital VOM Correctly

When measuring DC voltage in a circuit using a digital VOM (Volt-Ohm-Meter), it is important to pay attention to the polarity of the probes. The black probe is connected to the COM (Common/Ground/0 V) while the red probe is connected to the V pin (Highest electrical potential).

Electric potential is the amount of work done per unit charge, and it is represented as a difference between two points. When measuring voltage with the correct polarity, the VOM will display a positive value, indicating the difference in electrical potential between the two points.

However, if a mistake in polarity is made during measurement, the VOM will display the same value but with a different sign. For example, if the difference in electrical potential between point A and point B is 11V with the correct polarity, it will be displayed as +11V. But if the probes are reversed, the VOM will display -11V instead.

Therefore, it is crucial to ensure the correct polarity of the probes when measuring DC voltage with a digital VOM to obtain accurate readings. If a mistake is made, simply reverse the probes and measure again to correct the polarity and get the accurate result.