"N:dlzc D:aol T:com (dlzc)" escreveu na mensagem
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Dear Greg Neill:

"Greg Neill" wrote in message
m...
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No, in a propagating transverse electromagnetic
wave may be
orthogonal, but they are in phase.

In a vacuum they are in phase. As a medium in interposed, the phase
relationship changes. When bound to a conductor, and "pushing" charges
around, they are 90 degrees out-of-phase.

From my knowledge on power generation, the electric and
magnetic fields are 90 degrees out-of-phase if no mechanical
energy is converted into electric power.
For instance, a coil fed by AC current consumes no
power and has the electric field 90-degrees out-of-phase
from the magnetic field (if no mechanical power is
involved).

When mechanical power is converted into electricity
the fields (inside the air-gap where everything happens)
become 180-degrees out of phase for an unitary power
factor. A trivial power factor of 0.866 causes 150-degrees
out-of-phase.

What I didn't know was that in vacuum they are in-phase.
I guess it will be the other way around of the problem.
Light is converted into electricity, or mechanical action,
or whatever the sensor does to capture it, in-phase for
an unitary power factor.

Basically, being in-phase is the same as being 180-degrees
out-of-phase, since the directions of positive and negative
fields haven't been defined yet.

When both fields (electric and magnetic) are in phase, being
the electric field analogue to a potential (a sine wave voltage)
and the magnetic field analogue to a sine wave current, power
will be a sine square wave. Power is the product between
voltage and current and that's a sine square wave, which is a
wave with double frequency and half amplitude of the
original waves.

Concluding, if the fields are in-phase, light power will be
zero twice per cycle in vacuum.

What are the bases behind the claim that in vacuum
the electric and magnetic fields are in-phase?

Couldn't it be the case that electromagnetic radiation
in vacuum interacts with sensors in-phase for an
unitary power factor (and zero losses)?


http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html

David A. Smith