jerryyu Posted October 25, 2010 Share Posted October 25, 2010 and does all electromagnetic waves have the same amplitude? Link to comment Share on other sites More sharing options...
swansont Posted October 25, 2010 Share Posted October 25, 2010 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. Link to comment Share on other sites More sharing options...
TonyMcC Posted October 25, 2010 Share Posted October 25, 2010 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. Link to comment Share on other sites More sharing options...
physbod Posted January 27, 2011 Share Posted January 27, 2011 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! Link to comment Share on other sites More sharing options...
swansont Posted January 27, 2011 Share Posted January 27, 2011 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. Link to comment Share on other sites More sharing options...
alpha2cen Posted January 28, 2011 Share Posted January 28, 2011 (edited) and does all electromagnetic waves have the same amplitude? We can change polarity polarization of light by using organic matter. Edited January 28, 2011 by alpha2cen Link to comment Share on other sites More sharing options...
swansont Posted January 28, 2011 Share Posted January 28, 2011 We can change polarity of light by using organic matter. "polarity" (I assume this is polarization) ≠ amplitude Link to comment Share on other sites More sharing options...
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