The discussion centers on the speed at which light turns on after a switch is flipped, exploring the propagation of electrical signals and the behavior of electrons in a circuit. It touches on concepts of electrical fields, drift velocity, and the differences in response times among various types of light sources.
Participants express differing views on the speed of light and the behavior of electrons, with some agreement on the significance of the electrical field's propagation speed, but no consensus on the exact values or implications for different types of lighting.
There are limitations regarding the assumptions made about circuit configurations and the specific types of lamps discussed, which may affect the timing of light emission.
Oh, thank you! that clarifies a lot. One more question, regarding to the electrical field propagating "at a significant fraction of the speed of light", exactly how quickly is the propagation in comparison to the speed of light.Nugatory said:The change in the electrical field is what matters, and it propagates at a significant fraction of the speed of light - so we're talking maybe tens or hundreds of nanoseconds from switch closing to voltage across the filament of the light bulb.
The drift velocity of the electrons in the wire is much smaller, but that's something different. If you and I are holding opposite ends of a long metal rod and I pull on my end, you'll feel it almost immediately whether I pull quickly or slowly.