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Calculating resistance (Ohm’s Law)

Ohms law is an important and fundamental rule to remember when working with resistors and electronics in general. It defines the relationship between the componentsโ€™ current I in amps (A), voltage V in volts (V) and resistance R in ohms (ฮฉ). Ohmโ€™s law consists of three mathematical equations that explain the relationship between current, voltage and resistance. If you know two of these values, you can calculate the third using Ohmโ€™s Law. The three equations are:

I x R = V (current multiplied by resistance = voltage)
V รท R = I (voltage Divided by resistance = current)
V รท I = R (voltage divided by current = resistance)

Ohm's Law Image

Electrical power, measured in watts, can be calculated using Ohmโ€™s law. The power formula is P = V * I. If given voltage and current, this is easy to calculate by plugging in numbers. By substituting Ohmโ€™s formula, power can be calculated with resistance as well.

We have produced a handy online calculator to help with calculating the above formulas as well as other engineering calculators. These are just some of the options:

Ohmโ€™s Law Calculator
Max Resistor Power Calculator
PPM to % Converter
Other Engineering Calculators

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