Enter the test voltage (volts) and the test current (amps) into the Calculator. The calculator will evaluate the Rth.

## Rth Formula

Rth = Vtest/Itest

Variables:

- Rth is the Rth (ohms)
- Vtest is the test voltage (volts)
- Itest is the test current (amps)

To calculate Rth, divide the test voltage by the rest current.

## How to Calculate Rth?

The following steps outline how to calculate the Rth.

- First, determine the test voltage (volts).
- Next, determine the test current (amps).
- Next, gather the formula from above = Rth = Vtest/Itest.
- Finally, calculate the Rth.
- After inserting the variables and calculating the result, check your answer with the calculator above.

**Example Problem : **

Use the following variables as an example problem to test your knowledge.

test voltage (volts) = 75

test current (amps) = 100