Re: E=hv Question

[roger haar <haar@soliton.physics.arizona.edu>]

Hi

	The energy of any single photon is fixed and determined by its
wavelength.  The intensity of a beam of light is determined by
the number of photons.  Thus the energy of the beam of light is quantized
because the intensity is quantized.  That is the energy (E) of a beam of 
light is equal to the produce of the number of photons (n) and the energy
per photon E_photon.

	E = n E_photon = n h c / lambda

Where h is Planck's constant and c is the speed of light.

	It is true that you can get a beam of light with any energy 
by choosing the right wavelength, but in atomic physics on can 
get almost any energy level by choosing the right atom (you might have 
to shift the normal level slighly with electric or magnetic field to
get exactly what you want.



Thanks
roger Haar U of AZ
**************************************

On Mon, 14 Oct 1996, Chris Clayton wrote:

> At 02:27 PM 10/11/96 -0400, George Spagna wrote:
> > At 01:29 PM 10/11/96 -0400, Tony Wayne wrote:
> > > Given E=hv, when I increase the frequency I get more energy. What happens
> > > if I increase the amplitude of the E&M waves? What does this affect?
> >
> > The number of photons.  Intensity is proportional to the square of the field
> > in classical e-m waves.  Intensity is proportional to the number flux of
> > photons when you're counting photons.
>
>         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).
>
> Chris
>
> -- Chris Clayton  
> (first year physical science teacher)
> Mt. Zion Senior High School
> 305 S Henderson
> Mt. Zion, IL 62549
>
> email: misterc@uiuc.edu
> 	(currently forwarding to: clayton@webmart.net)
> MSN Chemistry Forum Assistant
> 	ChrisC_Asst@msn.com
>
> "Life is a vector quantity."