[ifuller]

Hello,
I have a question about the workings of neon lights.
I know that when you run electricity through a gas (say
hydrogen) the electrons are energized and jump up energy levels and
then cascade back down releasing photons. I also know that the
different energy levels emit different wavelengths of light as they
cascade down. Is there any way to control which level the electrons
jump to and therefore control the wavelengths of the light emitted by
the atom? Also is there a relationship between the intensity of light
and the current or voltage running through it? Thank you for any help
any one can offer.

[xiankai]

IIRC by varying the voltage by minute amounts (where energy supplied by W=V/C is equal to the difference between two subsequent energy states, or E_n-E_n-1), you should be able to control the maximum energy supplied to the electrons. however as this difference is very small, it is quite difficult to do so.

the greater the intensity of light, more photons are present/the incident light wave has more energy, so the current increases. voltage however is only related to how the light is produced - when an energy source is required before-hand.