jerryyu Posted October 25, 2010 Posted October 25, 2010 and does all electromagnetic waves have the same amplitude?
swansont Posted October 25, 2010 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.
TonyMcC Posted October 25, 2010 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.
physbod Posted January 27, 2011 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!
swansont Posted January 27, 2011 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.
alpha2cen Posted January 28, 2011 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
swansont Posted January 28, 2011 Posted January 28, 2011 We can change polarity of light by using organic matter. "polarity" (I assume this is polarization) ≠ amplitude
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now