Re: How is electrical power different from electrical energy?

Hello, JoyAnne!

Well, the difference is the same as it is for any type of energy and 
power; there's nothing special or different about electricity as far as 
that goes.

So, you ask, what is the difference between energy and power? The answer 
is that power measures how fast energy is used (or to be persnickety about 
it, it measures the rate at which work is done). The electric company, for 
example, charges you for the total amount of energy you use during a 
month, whereas the power rating on an appliance or light bulb tells you 
how fast that appliance or light bulb will use energy.

Suppose you have a 100 watt light bulb and you leave it turned on for 10 
hours. You have used 100 x 10 = 1000 watt-hours, or one kilowatt-hour, of 
energy. Now, if you replace it with a fluorescent bulb that is only 10 
watts, you would have to leave it on for 100 hours to use up the same 
amount of energy.

The electric company doesn't care - if you've used a total of one kilowatt 
it doesn't matter to them if it took you 10 hours, 100 hours, 5 minutes, 
or the whole month to do it. But if you know you're going to have your 
light on for 5 hours a day, you will use less energy if you use one that 
has a lower wattage rating.

For another example that doesn't involve electricity, let me tell you what 
I do in some of my classes. When you go up a certain vertical distance, 
you increase your gravitational potential energy by an amount that depends 
on that distance (specifically, it's your weight multiplied by the height 
you went up). So, in the large lecture hall I usually find myself in, I 
walk from the front up the stairs to the back, and point out that my 
potential energy has now increased. I then walk back down, turn around, 
and *run* up the stairs. I arrive at the top panting (I am not especially 
young!) and ask what is different? It's the same stairs, so the increase 
in my potential energy is the same, so how come I'm so out of breath where 
I wasn't before? Well, the difference is the time it took me to go up! The 
second time I went up a lot faster, so my potential energy increased a lot 
faster, which means that I used a lot more power (and tired myself out a 
lot more!).

Here is a link to a high-school-level tutorial on work, energy, and power; 
I hope it helps make things clear:
 http://www.glenbrook.k12.il.us/gbssci/phys/Class/energy/energtoc.html