The changing electric field creates current and between the plates of a capacitor, there exists displacement current. I wonder what happens when a lamp put between the plates of capacitor with no electrical conducting path? Does it light up? I really need help and if you find demo videos etc. would be really good. Thanks.

  • $\begingroup$ Can one run enough AC current trough a capacitor to power a lamp? Of course. The AC impedance of a capacitor is $Z=1/(i2\pi fC)$, i.e. it drops with frequency and capacitance and for many applications it can be made as small as a fraction of an $Ohm$. $\endgroup$
    – CuriousOne
    Apr 19 '16 at 7:29
  • $\begingroup$ @Canbeck Is the lamp between the plates of the capacitor with no electrical conducting path to it or is it connected to the capacitor plates with metal wires? $\endgroup$
    – Farcher
    Apr 19 '16 at 7:37
  • $\begingroup$ @Farcher I am sorry not to mension that. It is just put between the plates of the capacitor, there is no electrical conducting path between the lamp and the plates. $\endgroup$
    – Canberk
    Apr 19 '16 at 7:53
  • $\begingroup$ OK, don't do this at home... but one can easily set fire to aluminum foil with a microwave oven... that's exactly what you want. Now that you know: don't. Watch someone else do it on YouTube. $\endgroup$
    – CuriousOne
    Apr 19 '16 at 7:54

You may be interested in the following two references which seem similar to what you are asking about:



Quoting from the Guardian reference: A fluorescent tube glows when an electrical voltage is set up across it. The electric field set up inside the tube excites atoms of mercury gas, making them emit ultraviolet light. This invisible light strikes the phosphor coating on the glass tube, mak ing it glow. Because powerlines are typically 400,000volts, and Earth is at an electrical potential of zero volts, pylons create electric fields between the cables they carry and the ground.

If there is a difference of potential between the ends of a bulb a current will flow.

  • $\begingroup$ I looked at the paper, but I think these lamps light up because these long wires carry AC. The changing current creates changing B field and this produces EMF on these lamps. However, in my case, there is no varying B field, what I mean is there is no inductive EMF. This example looks irrelevant in this context. $\endgroup$
    – Canberk
    Apr 21 '16 at 10:00
  • $\begingroup$ I believe the accepted reason is that there is an electric field between the cable and the ground, so when you place the tube between them there is a difference in electrical potential between the ends of the lamp: pylons create electric fields between the cables they carry and the ground $\endgroup$
    – jim
    Apr 21 '16 at 10:48

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