If you know the current and resistance, which formula do you use to calculate power?

In electrical engineering, the relationship between power, current, and resistance can be described using Ohm’s Law and the power formulas derived from it. When you know the current (I) and resistance (R), the appropriate formula to calculate power (P) is P = I²R.

This formula shows that the power consumed in a resistive circuit is directly proportional to the square of the current flowing through the circuit multiplied by the resistance. This happens because power represents the rate at which energy is used or transformed, and when current flows through a resistance, some of that energy is converted into heat.

Using this formula is particularly useful in practical scenarios, such as when working with electric circuits where knowing the current and resistance helps in managing and predicting energy consumption and efficiency. It emphasizes how increasing the current significantly increases the power consumption due to the square relationship.

The other formulas provided do not fit the requirement of calculating power when you have the current and resistance. P = IV requires knowledge of voltage, while P = V/R expresses Ohm's Law rather than a direct formula for power. Finally, P = IR also does not reflect the current and resistance in a way that results in power calculations, as it suggests a different relationship altogether.