wrote:

I'm sure this is a simple question but I can't get a simple answer. If
high frequency waves can't penetrate water for more than a few
millimeters. Light is a high frequency wave (much more than 1MHz).
Why can I see light over 150 feet down?

Because water is transparent - though not to deep red. Absorption
requires a coupling to dissipate the energy. You walk in, you walk
out of successive reaction channels as frequency increases.

Calculate the skin depth of copper wire at 10^5 Hz

d = sqrt(2/wus)

where w = omega = (2pi)(10^5)
u = mu = copper magnetic permeability = (4pi)[10^(-7)]
s = sigma = copper conductivity = 5.8x10^7 mho/m.

This gives d = 0.21 mm. Rule of thumb is to use five times the skin
depth, so a 1.05 mm wire should work.

Applied Electromagnetism, Second Edition, Liang Chi Shen and Jin Au
Kong, PWS Publishers, 1987, p. 54, 57.


--
Uncle Al
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(Toxic URL! Unsafe for children and most mammals)
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