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Re: photoelectric effect



Now hold on there, Sam old buddy.

You say I've been teaching my students a common error for 40 years? I was
taught and I have continued to teach that the number of photons in a light
beam is directly proportional to the intensity of the beam. The energy of
the photons, however, is independent of the light's intensity but is
proportional to the wavelength of the light.

Did I mis-read your note or have I been wrong all these years?

poj

Samuel Held wrote:

Scott,
You have to be careful with your language. While the number of
photons reflected will be less than those incident, the intensity of the
reflected photons remains constant. It is a common error to associate
intensity with the number of photons. Intensity is actually the
magnitude of the energy they carry. My second point is that at any
boundary there is always some part that is reflected and some that is
transmitted thru the boundary to be refracted or absorbed. This is even
true of light, not all light is refracted when less than the critical
angle, some of it is reflected. Hope that helps.

Sam Held

-----Original Message-----
From: Scott Johnston [mailto:johnston@KIN.ON.NET]
Sent: Monday, June 28, 1999 4:51 AM
To: PHYS-L@LISTS.NAU.EDU
Subject: photoelectric effect

I need, once again, to access the distributed human computing power of
this
list.
A student of mine, while I was explaining the basics of the
photoelectric
effect, asked me if that process effected the way a metal would reflect
light.
Now, I had never been asked that before so I guessed it would and
explained
that the PE effect would pull down the reflected intensity of light
above
the threahold frequency for the metal involved. And then I started
thinking. By how much?
So the question is, what determines the relative magnitude of the
reflection of photons vs those absorbed through the PE effect?
My kind regards to all those who respond to this question.

This email comes to you from Kangaroo Island in South Australia. It is
an
isalnd with kangaroos.