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# Ohm's Law Calculator

A resistor is a perhaps the most common building block used in circuits. Resistors come in many shapes and sizes this tool is used to decode information for color banded axial lead resistors.

Enter any two values and click calculate to solve for the remaining value.

Voltage:
V

Current:
A

Resistance:
Ω

Power:
W

## Equations

Where:

• V = voltage
• I = current
• R = resistance
• P = power

Given any two values we can work out the third. This is called Ohms law; it's a simple formula and can be written in three ways depending on the value you need to work out.

Current calculation
I=V/R
Resistance calculation
R=V/I
Voltage calculation
V=IxR

Joule's Law is the rate at which heat is produced by a steady current in any part of an electric circuit and is jointly proportional to the resistance and the square of the current; this is expressed as a unit of Watts.

In resistive circuits, Joule's Law can be combined with Ohm's Law to produce alternative expressions for the amount of power dissipated, as shown below.

P = VxI
P = V2/R
P = I2xR