It is observed that high frequency electromagnetic waves as well as low frequency electromagnetic waves travel in the same medium with the same speed, but the low frequency electromagnetic waves penetrate deeper.
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$\begingroup$ It's unusual that the higher frequency waves penetrate deeper. Are you asking for a general discussion, or do you have a specific material in mind? $\endgroup$– FlorisCommented Apr 10, 2017 at 20:03
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$\begingroup$ I am looking for a general discussion. I came to think about it since I read a question suggesting the above thesis in a competitive exam paper in India. $\endgroup$– Sujai BanerjiCommented Apr 10, 2017 at 20:13
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$\begingroup$ Welcome to StackExchange. Please take a moment to complete the Tour so you know how this works: physics.stackexchange.com/Tour $\endgroup$– SDsolarCommented Apr 10, 2017 at 23:27
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$\begingroup$ @Floris: Sorry for the mistake in my question. Low frequency waves do penetrate deeper. I want to know the reason how frequency affects penetration power. $\endgroup$– Sujai BanerjiCommented Apr 11, 2017 at 20:37
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A dielectric medium typically has a complex dielectric constant (which is a function of frequency). Of this, the real part affects the propagation velocity of the wave; the imaginary part affects the loss. There is a property called the "loss angle" which is the angle "away from the real axis" of the complex dielectric constant. The larger the angle, the greater the loss per wavelength.
Note - at the same loss angle, the higher frequency will be attenuated more per unit length because there would be more wavelengths (and the loss angle describes loss per wavelength).
You can see some of the math behind this at this site,
