On Wed, 27 Aug 2003 19:49:14 -0500, W5DXP
wrote:

The optics physicists have done just fine understanding everything while
dealing with irradiance (average power). Instantaneous power is simply
not a very useful concept except in some esoteric applications.

Hi Cecil,

To date you haven't fielded many practical problems of "optics" as you
describe it. And the admission above is a poor excuse in place of
simple applications, never mind the esoteric ones you stumble over in
the dark bands.

A simple example which might offer you 50% chance of being right using
simple irradiance (average power, so average that their steady
illumination doesn't change during the entire time you ponder):

Which is brighter?
1.) 629 lux
2.) 5.0 millicandela/cm²

Which is visible in sunlight? (mark with an "x")
1.) _
2.) _
Sunlight being defined as the irradiance observed beneath the
equatorial Sun on the equinox at local noon on a cloudless day.

"If" you got any multiple guess right, a tougher question that
involves more skill and relates to the source power for each:

What is the source total intensity for each value above with either
source at 10 centimeters remote? (either source being isotropic)
1.) _____
2.) _____
expressed in Lumens total flux (or make it simple on yourself, Watts
total radiation)?

73's
Richard Clark, KB7QHC