and does all electromagnetic waves have the same amplitude?

Yes, it is possible; they don't all have the same amplitude. If it goes through a piece of glass, a small amount will reflect and the amplitude will go down. If the glass is tinted it will absorb light and the amplitude will go down even more. The amplitude is related to the brightness.

A radar transmitter uses several kV to generate power in the order of MW (peak). By the time it is received as an echo from a distant aircraft the power may well have a peak power measured in mW from which you may detect a a signal measured in mV. This is just one example of changing amplitude of an electromagnetic wave.

A radar transmitter uses several kV to generate power in the order of MW (peak). By the time it is received as an echo from a distant aircraft the power may well have a peak power measured in mW from which you may detect a a signal measured in mV. This is just one example of changing amplitude of an electromagnetic wave.

 

 

Well, yes, but doesn't the frequency of the EM wave determine the energy of each photon (E=hf)? So when the power decreases, what are we talking about here....fewer photons per second? I think the original query was talking about how, if at all, the physical amplitude/extent of the electric and magnetic field changes, if at all, and how can it be measured, if at all? I just can't visualise this and would really like to know!

Well, yes, but doesn't the frequency of the EM wave determine the energy of each photon (E=hf)? So when the power decreases, what are we talking about here....fewer photons per second? I think the original query was talking about how, if at all, the physical amplitude/extent of the electric and magnetic field changes, if at all, and how can it be measured, if at all? I just can't visualise this and would really like to know!

 

Yes, a lower amplitude means fewer photons per second. Fields add, so fewer photons result in a smaller field.

and does all electromagnetic waves have the same amplitude?

 

We can change polarity polarization of light by using organic matter.

Edited January 28, 201115 yr by alpha2cen

We can change polarity of light by using organic matter.

 

"polarity" (I assume this is polarization) ≠ amplitude