OK I have been debating this with some friends and they all disagree with me. Here is the question. If you have a simple circuit with a source switch and a load (lamp), you turn the switch on and then back off before the light comes on will the light still "blink"? From the source if there is 186,000 miles of wire it take exactly one second for the light to come on after closing the circuit. If you close it and open it before one second will the light come on for the amount of time you have it closed. I say that there would be no more emf to push the current so therefore it wouldn't light up. Do you know the answer? Please let me know what you think and why.

Thanks,

Chad

Thanks for the interersting question.

I believe it would light up.

If you imagine a very long pipe full of water, and turn a tap on for a second at one end, the water would not flow out of the other end immediately, but the shockwave of pressure would flow down the pipe at the speed of sound (in water). This water would come out the other end some time later for a second.

In the same way, the EMF creates a shockwave of charge moving through the electrons and this would carry on whether the EMF was still being supplied or not, and so the lamp would blink, yes.

I think the light would still turn on. Its similar to data being transmitted over, lets say a phone line, data is 1 and 0 alive or dead, on or off. The data still travels to the other end of the line, even when the originating side is not on any more, a similar affect would be to route a call around the world from your location, your phone, to a phone next to you. You say Hello, and there is a delay.

I'd say no it won't, you broke the circuit before anything could happen. A flow of electrons is needed to make a circuit work, if the electrons don't reach the lamp before the switch goes off the circuit is broken and the force moving them has disappeared.

Though this would be an interesting test if there was any way to do it.

Yes...

I agree with Lowtax4eva. The electrons would stop flowing, and since the flow was cut off before the light went on, it would not go on at all. I could be wrong. Also, you might want to take into consideration that the filament in the lamp must heat up before it can light, unless the question is purely theoretical (which it would pretty much have to be).

Does anyone understand what I am saying in that last sentence? I made it sort of confusing.

I'm telling you it will blink :p

Worthbeads and atlantaatax, do you disagree with my water pipe analogy?

I'm sorry but who really care's about a light comeing on 186,000 mile's away, try it if you need to know... good luck lol!

Sleeper, thanks for your contribution, but "who really cares" is not how human knowledge and understanding is advanced.

Did anybody figure the size wire for the voltage drop. Bulb would not light. And who would know?

Sorry start?

The bulb would not light because the circuit would be broken and the flow of electrons would stop.

Worth, if you imagine the water analogy, in your case you would end up with more water in one side of the circuit than the other, the water would still flow to even out the pressure.

Electricity is not water.

Quote:

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Originally Posted by Capuchin

worth, if you imagine the water analogy, in your case you would end up with more water in one side of the circuit than the other, the water would still flow to even out the pressure.

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Can't use the water analogy, because the pipe is full of water and the wire donot have electricity store in it, and if the pipe is full of water and it is vertical or incline water may not come out the other end or it even flow backward.. I think the lite won't blink, because the energy would dissipate as heat

The light will blink. While the circuit is closed electrons start moving, pushed along by the EMF of the power source. But because of the length of this circuit, the electrons don't all start moving at once: the EMF can only propagate through the wire at a speed a bit less than the speed of light (in typical cables the propagation of the electrical signal is around 2/3 the speed of light). So in effect there's a shockwave (as capuchin describes it) which is the front of the of electrons that are being pushed by the EMF. Now, when you disconnect the power source, the "news" that the power is no longer connected also travels down the wire at about 2/3 the speed of light. So the electrons in the vicinity of the light continue to feel the EMF until over a second after the power is turned off, and during that period electrons continue to move through the light filament and the bulb turns on.

It all comes down to the fact that nothing can travel faster than the speed of light, and in this case that includes the news that the power source is no longer connected.

If this is purely hypothetical , not taking into account for voltage drop and all. The light will light instantly when the switch is made. Electrons are like ping pong balls in a tube. If you push one in one end one will be pushed out the other end at the same time.

Regarding ping pong balls in a tube - the speed that the pressure waves moves down the tube to push those ping pong balls along is the speed of sound (through the ping pong balls) - substantially slower than the speed of light, and certainly not instantaneous!