Richard Clark wrote:

On Thu, 06 Sep 2007 12:47:46 -0700, K7ITM wrote:


On Sep 5, 5:02 pm, Jim Kelley wrote:
...

I'd like to offer m = E/c^2 as a guess.

73, ac6xg

"E=pc."

Yes, and p=mv, so when v=c as is true for photons, and we substitute
mc for p in the equation above and then solve for m (the mass of a
photon was the original question), we're back at the equation offered
previously.

But we usually relate more directly to the frequency (or wavelength)
of the photon rather than its energy or momentum, so in such a case
E=h*nu would provide a more direct route to its mass equivalent.

ac6xg