POWER RATING OF RESISTOR

The power rating of a resistor is one of the more hidden values. 

Every resistor has a specific maximum power rating. In order to keep the resistor from heating up too much, it’s important to make sure the power across a resistor is kept under it’s maximum rating. The power rating of a resistor is measured in watts, and it’s usually somewhere between ⅛W (0.125W) and 1W. Resistors with power ratings of more than 1W are usually referred to as power resistors, and are used specifically for their power dissipating abilities.

The power rating of a resistor is the specification given with a resistor that serves to tell the maximum amount of power that the resistor can withstand.

Measuring power across a resistor

Power is usually calculated by multiplying voltage and current (P = IV). But, by applying Ohm’s law, we can also use the resistance value in calculating power. If we know the current running through a resistor, we can calculate the power as:

Or, if we know the voltage across a resistor, the power can be calculated as: