And I have 100 of them.

The light bulb has burned out.

40 Watt incandescent lamp

100 Watt incandescent lamp

200 Watt incandescent lamp

No, your flashlight is meant to illuminate.

So for example, if we're looking at light bulb eight.

lasers, portable X Rays, shielding for nuclear reactors, compact discs, hybrid vehicle motors,

For us, we're very facile around electricity.

Edison invented the light bulb.

The light is out.

So I have one light bulb there.

I'm going to number them one through 100.

But I think you get the point.

So what's our question?

Here are the cables coming up into this light fixture.

As you might guess doing so would take a huge amount computation for even the most modest scene.

You know, this type of bulbs produces a lot of heat.

Noticed a bulb was out.

Thomas Edison invented the light bulb.

Thomas Edison invented the light bulb.

A little bit of differential, but not much.

The response to a bad idea

Well, let me actually just draw them.

So the first light bulb is light bulb one.

Light bulb three will be on.

The fifth light bulb would have been on and it'll stay on.

So the first pass, I switch every light bulb.

Four times four is 16.

36, 49, 64, 81, and 100.

Or I could say, I know that I'm going to switch light bulb 51, because 17 is a factor of 51.

But the pay off is really enormous.

Light came out of it in every direction.

And now I can start talking about parallel and series circuits.

And we can start talking about things like electrical load.

Light bulb two will be off.

So that's an interesting thing.

We always had electric lights,

The special, light emitting objects,

100 light bulbs.

So light bulb one will stay on.

The fourth light bulb will stay off, because I'm not touching it.

Well one, the only factor is just one.

And then we have these aircraft cabins.

(Knocks)