Enter the resistance (ohms), the current (amps), and the voltage drop (volts) into the calculator to determine the Source Voltage.

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## Source Voltage Formula

The following formula is used to calculate the Source Voltage.

Vs = R*I + Vd

- Where Vs is the Source Voltage (volts)
- R is the resistance (ohms)
- I is the current (amps)
- Vd is the voltage drop (volts)

To calculate the source voltage, multiply the resistance by the current, then add the voltage drop.

## How to Calculate Source Voltage?

The following example problems outline how to calculate Source Voltage.

**Example Problem #1**

- First, determine the resistance (ohms). In this example, the resistance (ohms) is determined to be 4 .
- Next, determine the current (amps). For this problem, the current (amps) is measured to be 5 .
- Next, determine the voltage drop (volts). In this case, the voltage drop (volts) is found to be 20.
- Finally, calculate the Source Voltage using the formula above:

Vs = R*I + Vd

Inserting the values from above and solving the equation yields:

Vs = 4*5 + 20 = 40 (volts)

**Example Problem #2**

Using the same method as above, determine the variables required by the equation. For this example problem, these are:

resistance (ohms) = 3

current (amps) = 6

voltage drop (volts) = 30

Enter these given values into the calculator or above yields:

Vs = 3*6 + 30 = 48 (volts)