PHYS 3320: Electricity and Magnetism II

Electricity and Magnetism IIGriffiths Chapter 9 EM WavesClicker Questions

9.1A function, f(x,t), satisfies this PDE:

Invent two different functions f(x,t) that solve this equation. Try to make one of them boring and the other interesting in some way. 9.222CLASS ACTIVITY, NOT A CLICKER QUESTION________________________________Physics 3320, Fa11 (SJP) Lecture #20________________________________Fall 2011 CommentsEnded class (w, gamma->0).

==============================From ERK Fall 2009WaveguidesThe following questions are from Ed Kinneys Sp11 E&M II course Waveguides were not covered in Fa11 or Sp12 at CU

9.8888What is the electric field in a perfect conductor if an EM wave is incident on the surface?A. ZeroB. Depends on the angle of incidenceC. Depends on whether the EM wave is in a dielectric or vacuumD. Perfectly in phase with the incident wave but decreasing with distance into the conductorE. Not enough information to say

9.89Class: CONCEPTUALCorrect Answer: A_________________________

========================From ERK Fall 2009What is the magnetic field in a perfect conductor if an EM wave is incident on the surface?A. ZeroB. Depends on the angle of incidenceC. Depends on whether the EM wave is in a dielectric or vacuumD. Out of phase with the incident wave and decreasing with distance into the conductorE. Not enough information to say

9.90Class: CONCEPTUALCorrect Answer: A_________________________

========================From ERK Fall 2009Which of Maxwells equations, when applied to regular plane wave solutions

required that the electric field was transverse?A. Gauss Law for the electric fieldB. Gauss Law for the magnetic fieldC. Faradays LawD. Amperes LawE. More than one Maxwell equation was required

9.91Class: CONCEPTUALCorrect Answer: _________________________

========================From ERK Fall 2009The separation of variables technique gives us 2 ODEs of the formA. It doesnt matter which we choose, either choice will workB. The wave equation itself determines the signsC. The boundary conditions at the walls determine the signsD. None of the aboveE. More than one of the above

On what basis can we determine whether to use a positive or a negative separation constant c2?9.92Class: MATHCorrect Answer: _________________________

========================From ERK Fall 2009For TEmn modes we found the general dispersion relationA. Only TE10 B. All modes, except TE10 and TE01 C. Only TE10 and TE01D. None of the aboveE. Not enough information

For the case a = 2b, waves with = 1.01c/b are input to the waveguide. Which TEmn modes can be used to transport the input wave?

with9.93Class: CONCEPTUALCorrect Answer: _________________________

========================From ERK Fall 2009For TEmn modes we found the general dispersion relationA. mn/kB. /kC. cD.E. None of the above

What is the phase velocity of the waves in the waveguide?

with

9.94Class: MATH/ PHYSICSCorrect Answer: _________________________

========================From ERK Fall 2009For TEmn modes we found the general dispersion relationA. The TE mode wavelength is larger than the plane waves.B. The TE mode wavelength is smaller than the plane waves.C. The TE mode wavelength is the same as the plane waves.D. The answer depends on the actual value of the frequency.E. The answer depends on the actual values of the side lengths.

How does the wavelength a TE mode compare to that of a plane wave in vacuum with the same frequency?

with9.95Class: CONCEPTUALCorrect Answer: _________________________

========================From ERK Fall 2009