Just For Fun...

Q: When you turn on a light switch, there is a tiny but measurable interval before the light comes on. How long does it take? What causes any delay-are you waiting for the electrons in the wires to reach the light bulb? Once the current is flowing, how soon does the light bulb begin emitting visible light?

A: Electrons move through the circuit at a relatively slow speed of 10^-4 m/s, but the 'signal'—the change in the electric field along the wire—moves at nearly the speed of light. It is the signal rather than the actual electrons from the wire in the light switch that must reach the light bulb. The signal may reach the filament in the bulb in as little as a nanosecond (10^-9 s), hardly enough time to bother measuring. However, the filament must first be heated by the current flowing through it before it can emit light. To emit visible light, the filament must reach several thousand degrees Kelvin; that temperature is typically reached 0.01 to 0.1 second after the switch is thrown.

From "The Flying Circus of Physics," by Jearl Walker, publishers John Wiley & Sons, 1977, New York

It's a banana plug.