What's a Watt? (part 1)

What's a Watt? (for non-engineers) - Part 1

I'm an engineer.  While having a discussion on energy efficiency once with a non-engineer, they exclaimed, "I'm not an engineer, I don't have to know what a Watt is to save energy!"  Well, needless to say (I am spending my night writing this blog after all), I completely disagree.

To paraphrase Sun Tzu: Know your Enemy!  While the Watt is not necessarily our enemy (it does do a lot of good for us), wasteful Watts are definitely our enemy.  And how can we truly understand how to defeat them, if we don't really understand what they are?

The extremely simple explanation of a Watt is that it is Voltage (Force) multiplied by Current (Electron flow).  There you go.  Now you understand right?  Well, not really.  That explanation is pretty hard to visualize isn't it?

(read the following explanation, then watch slide show at the end!)

The easiest way to envision the Watt is to start with the image of water as it flows through a pipe.  In this case, the pipe is directly above your head and you are standing on the bottom of a cavern floor (I hope you put on your imagination hat).  The pipe runs up through the cavern, through the rock above, and into a small reservoir.

Luckily for you, there is a raft floating on top of the reservoir, and the major characters from the Dreamworks film, Shrek, standing on the shore(please, bear with me!).  Controlling how much the valve opens - and how much water you get on your head - is the Fairy Godmother (she was evil after all).

(the slide show will run automatically, but may be slow, so feel free to click through it.  Make sure you make it to the summary page at the end.)

View more presentations from ckmapawatt. (tags: watts current)

Let's say the Fairy Godmother is only slightly annoyed with you.  She may only open the valve a little bit, letting a few drops on your head; thus, a small amount of current (in this case, current refers to the flow of water droplets.  The flow of electrons is also referred to as current).  As you continue to annoy her, she opens the valve more and more, allowing more and more water to flow through it, and increasing the current of water that is landing atop your head.  The water does not hit you any harder, there is just more of it hitting you.  But you are strong, and to her consternation, you remain standing, albeit soaking.

You remain standing because the power the water is exerting on your head is not enough to knock you down.  The power contained in the water is not simply made up of its current (how fast it's flowing - in this case controlled by how far the valve is opened) but also by how much force is behind that flow.  In this case, the force is going to be supplied by the weight of the Shrek characters as Fairy Godmother slings them onto the raft.

If at first, Fairy Godmother only places Pinocchio into the raft, you might feel the water hit a little harder, but probably not enough to knock you down.  As she adds characters -adding force (voltage in terms of electricity), the water is going to be hitting you with more and more power (Watts).  Until finally she throws Shrek (he's a heavy guy, so exerts more force on the water) on there and knocks you to your feet!

The power (Watts) the water exerts on your head depends on two things: how far the valve is open (how much water - or current - is let through) and how much force is behind that current (how much weight -provided by the characters  - is on the raft - voltage in terms of electricity)!

So just like the water power that was needed to knock you down was the product of the water flow and the force the Shrek characters applied to the water, the power (Watts) coming out of your electrical socket is a product of the electron flow (current, referred to as Amps) and the force applied to those electrons (voltage, referred to as Volts).

So there you have your watt!

See how this applies to your home in part 2...

enjoyed our post? let others know: 


Thank-you for putting such an abstract concept in concrete lay terms. It is the first time I am able to fully understand the difference between, current, volts, watts. You did not get into oms though.
I think of electricity as a water fall: The higher the water fall, the higher the voltage. The wider the water fall, the lower the resistance. The quantity of water flowing per second is the current (amperage). So, the wattage is "water quantity times water fall height"
ckmapawatt's picture
That's actually a great analogy. I've always used the water in the pipe analogy, but it's sometimes hard to get across the voltage aspect of that.

Post new comment

Subscribe to Comments for "What's a Watt? (part 1)"