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How do you Calculate Power across a Resistor?

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Editorial Team - everything PE

Jan 9, 2023

Power across a resistor can be measured by using 3 basic formulas based on Ohm’s law.

Where P = Power, V = Voltage and I = Current

 According to Ohm’s Law,

Where R = Resistance, V = Voltage and I = Current

 If we rewrite the Power equation in terms of resistance, we will get two equations: Power in terms of Resistance and Voltage, and Power in terms of Resistance and Current.

and

 

Note: The unit of power is Watts (W).

Let’s take an example to better understand this.

Consider the above circuit. Here, 

Resistance, R = 100 Ω 

Voltage, V = 10 V 

Based on the given values we will calculate the Power across the resistor using the power formula in terms of resistance and voltage.