[JonathonW]

The further the battery and switch get away from the light, the less current you'll see at the battery at (sqrt(2)*width)/c s, since the electric and magnetic fields around the battery and wire will drop in strength as you move further away from them.

Put another way, the main reason this effect is observable in the way shown in the video is because the light and battery, and the wires between them, are so close together. Move them further away, and, per the inverse square law, you'll start seeing a much lower induced current-- the effect may still be there, but it won't be measurable over the noise floor of the experiment setup.

[bsder]

You're right, but sorta. Which is the big problem here, any simplified analogies break down.

What's happening is that you are straying further and further from the "impedance matched" condition (the inductance per unit length stays the same but the capacitance goes up with the separation--however, being "too close" will also cause similar behavior). Consequently, the energy transmitted per reflection gets smaller and smaller.

Part of the problem in this whole discussion is using a "light" as a "threshold detector" where the threshold is effectively microamps. A microamp threshold detector is not what people think of as a "lamp".

If the original Veritasium video had showed the current flow via meter, oscilloscope, etc. nobody would be terribly surprised as it would show small flows getting bigger upon each reflection until it built up to the full current.

[junon]

This makes more sense and was my first thought watching the video.

Question: At which point does the influence reach actual zero? If it doesn't, does that mean the coffee in front of me is being influenced by Jupiter, however minuscule?

[smsm42]

In field theory, IIRC, fields (absent special setups, i.e. in space) are never actual zero, but due to reverse square law they become too small to actually care about quite soon. But the quantum model may have some limitations on that, since stuff can't be arbitrarily small there AFAIK. Not sure what happens about the gravity - likely, Jupiter might influence your coffee, even though in an immeasurably small way, since gravity is very weak. We know the Moon influences our oceans quite prominently. But maybe there are minimums there too?