RE: Properties of Light - EM waves/particles

Carrigan, Ken ( (no email) )
Wed, 6 Oct 1999 10:57:50 -0400

If a beam of light passes from one media to another and if the speed
of the light is different (>='c') in the two media's, then the light
will be refracted with a predetermined angle. For example take a two
materials one ontop of another. Assume the speed is slower in the
lower material, to be less than 'v', the speed in the upper material,
the wavefronts will be closer together in the lower material. This
must be true since the number of crests (frequency) passing from
upper and lower material per second MUST be the same, and equal to
the frequency 'f' of the wave. The frequency does not change at
all, if it did, there would either be a 'piling up' of wave crests
between the two media or disappearance of wave crests - which there
is not. So, the time taken for a wavecrest to traverse one wavelength
in the upper material MUST equal the time in the lower material -
and thus lambda1/velocity1 = lambda2/velocity2.

{Russ stated:}
>Thank you for all the interesting replies, there is definitely some food
for
>thought in there. I am surprised to see that no one touched upon my
statement
>about waves needing a medium to propagate through. My understanding with
waves
>is that they are carried by the vibration of atoms, thus why sound cannot
be
>heard in a vacuum. How can this be different for light, unless there is
some
>other phenomena in a the vacuum carrying the light waves. Lets look at
another
>property of light, which is heat. Heat transference needs a conductor of
some
>sort, again something that would be missing in a vacuum, so how do we feel
heat
>from the sun if there are no molecules to transfer the heat?

Ah, but Photons are not only waves but have properties of mass also. For
example, relativistics of mass states m = m0/sqrt(1- (v/c)^2) such that as
the particle speed 'v' increases to 'c' the mass becomes infinite! hence
you need a huge amount of energy to move it close to 'c' and never can
exceed it. Applying this to a photon, where 'v' IS 'c' the mass becomes
infinite thus we can say.. there is NO mass to a photon since it can not
be infinite in mass, when traveling at 'c'. However, we can set Einstien's
mc^2 equal to the energy of a photon or hv and thus come out with mc =
hv/(c)
or the momentum of a photon. This quality was measured by letting
electromagnetic radiation collide with matter in 1923 - Compton, also in
around 1960 an experiment was made to measure the gravitational mass of a
photon, by the Mossbauer effect. Both showed that a photon has properties
of mass, and also of a wave.

v/r Ken Carrigan

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