# Electrical Energy and Power

1. Mar 12, 2007

### AznBoi

Can someone please explain the difference between these three equations? I'm having trouble understanding their meanings and have no idea when I should use each one. Thanks.

$$P= I \Delta V$$

$$P= I^{2}R = \frac{\Delta V^{2}} {R}$$

2. Mar 12, 2007

### mjsd

they all gives you power P. depending of the situation, you may be given or could work out only two of them and not all. for instance, if you know a battery is pumping 0.3A into a circuit and across its terminal it is 3V then power the battery is providing is P=VI=0.3x3=0.9W. for another instance, you may want to calculate power dissipated at a load of resistance R, then if you know the current through it, you can work out P=I^2 R.