3 1-18.   H lines have which of the following distinctive characteristics? 1.  They are continuous straight lines 2.  They are generated by voltage 3.  They form closed loops 4.  They form only in the wave-guide 1-19.   What minimum number of boundary conditions must be satisfied for energy to travel down a waveguide? 1.  One 2.  Two 3.  Three 4.  Four 1-20.   For an electric field to exist at the surface of a conductor, the field must have what angular relationship to the conductor? 1.    0 degrees 2.  30 degrees 3.  45 degrees 4.  90 degrees 1-21.   What, if anything, happens to the amplitude of the wavefronts within a waveguide that DO NOT meet boundary conditions? 1.  They Increase rapidly to maximum 2.  They decrease slowly to the half- power point 3.  They decrease rapidly to zero 4.  Nothing 1-22.   If the wall of a wave-guide is perfectly flat, the angle of reflection is equal to which of the following angles? 1.  Angle of cutoff 2.  Angle of incidence 3.  Angle of refraction 4.  Angle of penetration 1-23.   THIS QUESTION HAS BEEN DELETED. 1-24.   How does the group velocity of an electromagnetic field in a waveguide   compare to the velocity of a wavefront through free space? 1.  Group velocity is faster 2.  Group velocity is slower 3.  Their velocities are the same 1-25.   The group velocity of a wavefront in a waveguide may be increased by which of the following actions? 1.  Decreasing the frequency of the input energy 2.  Increasing the frequency of the input energy 3.  Increasing the power of the input energy 4.  Decreasing the power of the input energy 1-26.   The various field configurations that can exist in a waveguide are referred to as 1.  wavefronts 2.  modes of operation 3.  fields of operation 4.  fields of distribution 1-27.   The most efficient transfer of energy occurs in a waveguide in the what mode? 1.  Sine 2.  Dominant 3.  Transverse 4.  Time-phase 1-28.   How is the cutoff wavelength for a circular waveguide figured? 1.  1.17 times the radius of the waveguide 2.  1.17 times the diameter of the waveguide 3.  1.71 times the diameter of the waveguide 4.  1.71 times the radius of the waveguide