Power Three Ways - Electronic Circuits II Step by Step

The same resistor power can be computed by voltage-current, current-resistance, or voltage-resistance routes. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

Start from the same checked current

The source is 12 volts and the resistor is 6 ohm, so the current is 2 amperes.

I = \frac{V}{R} = 2\ \text{A}

Three power formulas agree

The helper checks the three exact routes and gets 24 watts each time.

P = V I = I^{2} R = \frac{V^{2}}{R} = 24\ \text{W}