Re: E=hv Question

["John E. Sohl" <JSOHL@cc.weber.edu>]

Chris wrote:

>        If I read this right, then the *intensity* is quantized, not the
> *energy*.  I know that energy _levels_ are quantized in atoms.  It just
> strikes me because whenever these topics came up in my chemistry classes the
> equation E=hv is referred to (or butchered as) the quantization of energy
> and from the equation that is not at all obvious (and probably wrong).

	An interesting observation Chris.

	Any given photon carries a fixed amount of energy (a small "packet" of 
energy, if you will) of the amount E=hv. Thus, as the light arrives at a 
detector (eye, PMT, atom, etc.) it arrives in distinct packets or quanta.

	Since any frequency of photon can be created, then you might conclude
that energy is not quantized. But the point is that whatever the energy is that
you have, it will arrive/depart in chunks. Thus, you are completely correct to
conclude that (for quasimonochromatic light) the intensity is quantized. But so
is the energy, since it is delivered in quanta. Compare this to classical heat,
in this case, the energy is NOT delivered in chunks. (Before, I get flamed, I
do know about phonons....)

	Note that for polychromatic light, the intensity might no longer be
truly quantized since you can add photons of different frequencies to obtain an
effectively continuous increase in total intensity.

John Sohl, Associate Professor & Laser Jock, Department of Physics
Director, Layton P. Ott Planetarium
Weber State University, Ogden, Utah, USA 84408-2508
voice: (801) 626-7907    FAX: (801) 626-7445
JSOHL@WEBER.EDU