Explanation and example

For an ohmic component, Ohm’s law relates voltage U, current I and resistance R: U = I × R. Leave one field blank. Values use volts, amperes and ohms. We also calculate electrical power with P = U × I after resolving the missing value.

Example: a 12 V supply across a 6 Ω resistor gives 2 A and 24 W. Check the result by multiplying 2 A by 6 Ω to obtain 12 V. Given voltage and current, divide U by I to find R.

Limits

The relationship assumes resistance stays approximately constant under the stated conditions. A diode, a heating filament or an AC circuit may require another model. Zero current and zero voltage do not determine a unique resistance.