Multisim and Ultiboard
voltage difference
Hi libby6295,
No, the circuit’s reference point should not have an effect on the voltage difference across any resistor.
The circuit’s reference point only affects the node voltages at the resistor's terminals but not the voltage drop across the resistor. This is because the voltage drop across a resistor should generally be measured differentially (the voltage drop across a resistor is the difference between the voltages that exists on its terminals). The exception is when one terminal of the resistor is on the circuit reference point, in this case a simple (single-ended) measurement can (also) be employed.
In the circuit below, the node voltages at the ends of Rbint (10 Ω) are measured using probes PR1 and PR2 which have GROUND as reference point. The voltage drop across Rbint is measured using probe PR3 which is paired with reference REF1 so that PR3 will automatically display the voltage drop across Rbint.
The Configuration Pane for probe PR1 is shown below, note that the Voltage reference is Ground (this is in red circle). Similarly, PR2 will also have Ground as Voltage reference.
The Configuration Pane for probe PR3 is shown below, note that the Voltage reference is REF1 (this is in red circle).
Below is a simulation run of the circuit. Carefully read the measured values and note that GROUND (the circuit reference point) is in the usual place.
By moving the GROUND (the circuit reference point) to a different location we can see that the values shown by probes PR1 and PR2 change but PR3 displays the same value.
I hope that through the explanation and simulation screenshots you are convinced that the voltage across Rbint did not change (stayed at 237.62 mV) even when GROUND (the circuit reference point) was relocated.
For reference you can open these Multisim Live Help pages:
Best regards,
G. Goodwin
