We have a plane electromagnetic wave traveling in the +z direction. As you may recall, plane waves have electric and magnetic fields that vary like either sine or cosine, with an argument of (kz−ωt). Our goal here will be to write down the equations describing the electric and magnetic fields in this particular wave, and then use those equations to calculate a few quantities. Let's suppose that at z=0 and t=0, the magnetic field has its maximum value B0 and points in the −y direction. Use that information to decide whether your B -field should vary like sine or like cosine, and write a symbolic vector expression for B . Then write a symbolic vector expression for the E -field that would be in this wave. The definition of the Poynting vector will let you figure the direction of the E -field. a) Now let's suppose that B0 =0.0042 T. What is the scalar value of the electric field at t=0? Note that this could be positive or negative. b) What is the magnitude of the Poynting vector of this wave at t=0? c) The frequency of this wave is f=2.100e+06 Hz. What is the scalar value of the magnetic field at t=1.21e−07 s? You can still assume that z=0.
We have a plane
Let's suppose that at z=0 and t=0, the magnetic field has its maximum value B0 and points in the −y direction. Use that information to decide whether your B -field should vary like sine or like cosine, and write a symbolic vector expression for B . Then write a symbolic vector expression for the E -field that would be in this wave. The definition of the Poynting vector will let you figure the direction of the E -field.
a) Now let's suppose that B0 =0.0042 T. What is the scalar value of the electric field at t=0? Note that this could be positive or negative.
b) What is the magnitude of the Poynting vector of this wave at t=0?
c) The frequency of this wave is f=2.100e+06 Hz. What is the scalar value of the magnetic field at t=1.21e−07 s? You can still assume that z=0.
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