Ohms Law Calculator and Tutorial
Enter any two known values, select units and press Submit to solve for the others.
Ohm's Law Explained
Ohm's Law is the relationship of any DC circuit between Voltage, Current and Resistance first discovered by German physicist Georg Ohm. It states that if current is applied across a conductor between two points is directly proportional to the voltage across the two points. Knowing any two values, you will be able to solve for the missing value. A great way to remember the formula is to use Ohms triangle where Voltage is on top and Current and Resistance are on the lower left and right sections.
Ohms Triangle
To Find Voltage
V = I x R
Finding the voltage using the triangle you will need to know the Current (I) and the Resistance (R). Multiple the I X R to find the voltage
Formula: V = I x R
Example: 2A x 20Ω = 40V
To Find Current
I = V / R
Finding the current using the triangle you will need to know the Voltage (V) and the Resistance (R). Divide the V by R to find the current
Formula: I = V / R
Example: 40V / 20Ω = 2A
To Find Resistance
R = V / I
Finding the resistance using the triangle you will need to know the Voltage (V) and the Current (I). Divide the V by I to find the resistance
Formula: R = V / I
Example: 40V / 2A = 20Ω
Commonly the letter (V) is used to represent Voltage, (I) is used to represent Current and (R) is used to represent Resistance.
Electrical Power Explained
Electrical Power (P) or watts is the rate at which energy is absorbed or produced within a circuit. Power is prdouced by many sources such as generators, batteries, solar, wind and other sources. The power is then supplied to homes and businesses. The same principals apply as before. If you know two values you can solve for the others.
Power Triangle
To Find Power
P = I x V
Finding the power using the triangle you will need to know the Current (I) and the Voltage (V). Multiple the I X V to find the power
Formula: P = I x V
Example: 2A x 40V = 80W
To Find Current
I = P / V
Finding the current using the triangle you will need to know the Power (P) and the Voltage (V). Divide the P by V to find the current
Formula: I = P / V
Example: 80W / 40V = 2A
To Find Voltage
V = P / I
Finding the voltage using the triangle you will need to know the Power (V) and the Current (I). Divide the P by I to find the voltage
Formula: V = P / I
Example: 80W / 2A = 40V