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Ohm's Law and Ohms Law Calculator

Ohm's Law and Formulas

Ohm's Law [after physicist Georg Ohm] states that: In an electrical circuit, the current which passes through a conductor between two points is proportional to the potential difference (i.e. voltage drop or voltage) across the two points, and inversely proportional to the resistance between the two point. In mathematical terms, this is expressed as:

I=V/R or V=IR

where I is the current in amperes, V is the potential difference (voltage drop or voltage) in volts, and R is the resistance which is measured in ohms.

The instantaneous electrical power P delivered to a component is the product of voltage and current, which may be expressed in mathematical terms as:


where P is the instantaneous power in watts (joules per second or volt-amperes). The terms I, R and V are as described above.

Ohms Law Formula Wheel

Use the Ohms law formula wheel below for all the mathematical relationships between P, I, V and R.

Ohm's Law Formula Wheel

Ohm's Law Formula Wheel

Ohm's Law Calculator

You can use this online calculator to apply Ohm's Law. To use the calculator, enter any two known values and press the "Calculate" button to solve for the unknown values.

NOTE: This online calculator requires that JavaScript be enabled on your browser.

Voltage (V)
Current (I)
Resistance (R)
Power (P)

Ohm's Law Calculator

Remember to "Clear" all the fields prior to starting a new Ohm's Law calculation.