Ohm's Law

What is Ohm's Law - You are most likely here because you are curious to what Ohm's law is. At some point during your journey to becoming a BassHead you will need to be able to calculate how much resistance you need for a given situation, how much current a circuit will pull, or how much voltage will be dropped between two points in a circuit. All of these calculations can be made by using one of the following formulas derived from Ohm’s Law.

With Ohm's Law you will be able to tell through Clamp Testing how much resistance you see, how much amperage you are drawing and be able to calculate your real time wattage output.

Ohm's law circle cut out:
Print, cut out and become an expert calculator!
To use the wheel you find the 'missing value' in the middle and look to the outer edge to find the 2 values you have, then calculate. An important point to note is that you must use the correct units of measurement for the calculations or you will get incorrect answers. You must use Amps, Ohms, Volts and Watts. If you have kiloOhms, milliVolts etc. you must convert first.


*Don't have a calculator on hand? Check out this awesome Ohm's Law Calculator



Ohms calculations

The resistance R in ohms (Ω) is equal to the voltage V in volts (V) divided by the current I in amps (A):

The resistance R in ohms (Ω) is equal to the squared voltage V in volts (V) divided by the power P in watts (W):

The resistance R in ohms (Ω) is equal to the power P in watts (W) divided by the squared current I in amps (A):

Amps calculations

The current I in amps (A) is equal to the voltage V in volts (V) divided by the resistance R in ohms (Ω):

The current I in amps (A) is equal to the power P in watts (W) divided by the voltage V in volts (V):

The current I in amps (A) is equal to the square root of the power P in watts (W) divided by the resistance R in ohms (Ω):

Volts calculations

The voltage V in volts (V) is equal to the current I in amps (A) times the resistance R in ohms (Ω):

The voltage V in volts (V) is equal to the power P in watts (W) divided by the current I in amps (A):

The voltage V in volts (V) is equal to the square root of the power P in watts (W) times the resistance R in ohms (Ω):

Watts calculation

The power P in watts (W) is equal to the voltage V in volts (V) times the current I in amps (A):

The power P in watts (W) is equal to the squared voltage V in volts (V) divided by the resistance R in ohms (Ω):

The power P in watts (W) is equal to the squared current I in amps (A) times the resistance R in ohms (Ω):