Tom Donaly wrote:

How many photons does it take to make a Watt?

1/(Hz*6.63*10^-34).

The lower the frequency the less energy per photon.

John Popelish wrote:

Tom Donaly wrote:

How many photons does it take to make a Watt?


1/(Hz*6.63*10^-34).

The lower the frequency the less energy per photon.

That's joules per second, is it?
73,
Tom Donaly, KA6RUH

Tom Donaly wrote:
John Popelish wrote:

Tom Donaly wrote:

How many photons does it take to make a Watt?



1/(Hz*6.63*10^-34).

The lower the frequency the less energy per photon.


That's joules per second, is it?

A watt is a joule per second. The formula gives the number of photons
per second that carry a watt (or a joule per second) once you provide
the Hz (frequency).

By the way, I am having second thoughts as to whether or not there
should be a 2*pi factor in there, since most physics formulas deal
with frequency in radians per second, not cycles per second. But the
photon energy formulas usually deal with wavelength, and I have never
seen one that assumes a wavelength is a radian of a cycle, rather that
a full cycle, so, perhaps Hz is the correct unit.

If anyone can clear this up for me, I would appreciate it.

On Tue, 11 Jul 2006 11:06:19 -0400, John Popelish
wrote:

By the way, I am having second thoughts as to whether or not there
should be a 2*pi factor in there, since most physics formulas deal
with frequency in radians per second, not cycles per second. But the
photon energy formulas usually deal with wavelength, and I have never
seen one that assumes a wavelength is a radian of a cycle, rather that
a full cycle, so, perhaps Hz is the correct unit.

If anyone can clear this up for me, I would appreciate it.

Hi John,

That would be 2 pi radians per second as frequency - same thing as a
cycle. For photonic interactions the classic treatment is usually
with wavenumber as frequency not cycles nor radians. However, the 2
pi difference is the difference between the Planck constant
represented as h, and its rational equivalent (with 2 pi divided out)
of h-bar.

73's
Richard Clark, KB7QHC

Richard Clark wrote:
On Tue, 11 Jul 2006 11:06:19 -0400, John Popelish
wrote:


By the way, I am having second thoughts as to whether or not there
should be a 2*pi factor in there, since most physics formulas deal
with frequency in radians per second, not cycles per second. But the
photon energy formulas usually deal with wavelength, and I have never
seen one that assumes a wavelength is a radian of a cycle, rather that
a full cycle, so, perhaps Hz is the correct unit.

If anyone can clear this up for me, I would appreciate it.


Hi John,

That would be 2 pi radians per second as frequency - same thing as a
cycle. For photonic interactions the classic treatment is usually
with wavenumber as frequency not cycles nor radians. However, the 2
pi difference is the difference between the Planck constant
represented as h, and its rational equivalent (with 2 pi divided out)
of h-bar.

Thank you. Makes good sense.