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Zero Voltage Or Reference Voltage Level in Electronic Circuit

Zero Voltage Or Reference Voltage Level

The measurement of the Voltage or Electro-Motive Force can only be done with relative to a reference level or reference point.

For example when we say a Battery is of 12 Voltage that means the difference in the Voltage or EMF of the positive terminal to the Reference level which is the negative terminal normally is 12 voltage as shown in the figure above.

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Electromotive force (EMF)
Voltage Source and Current Source
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The use of Reference Voltage Level is done in order to avoid errors in the measurement of Voltage in various points of a circuit. The Reference Voltage Level or the common point is considered to be of zero potential and all other circuit voltages weather positive or negative , are measured with respect to this Common or Reference Voltage Level.

There is no hard and fast rule for the selection of the common point or Reference Voltage Level , any point in the circuit can be regarded as the Reference Voltage Level and all the electronics theorems and theorems will be still true in the circuit if all the measurements are done correctly with respect to the common point.

For example:

Case I:

In the Image Above: The point shown or the negative terminal of the battery is regarded as the Common Zero Reference Level.
Then , the potential of the given points are as follows:

A:- 0 Voltage
B:- 7 Voltage ( Just a Guess)
C:- 12 Voltage

Case II:
We can also equally now regard the point B as the Zero reference level as shown in the figure:

And now instead of the point A ; Point B is now the ZRl , The voltage measurement of the points will be:

A:- -7 Voltage ( Just a Guess with in accordance with the measurements in case I)
B:- 0 Voltage
C:- +5 Voltage ( in accordance with the measurements in case I)

For correct voltage measurement The negative terminal of the Voltage Meter should be connected to the ZRL or Common point and the positive terminal of the meter is connected to the point of which potential is to be measured , as shown in the figure below:

The Zero Reference Level is also grounded in most of the circuits.

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