2 1-9.   At very high frequencies, ordinary insulators in a two-wire transmission line display the characteristics of what electrical component? 1.   An inductor 2.   A resistor 3.   A capacitor 4.   A transformer 1-10.   At very high frequencies, which of the following devices works best as an insulator? 1.   Open half-wave section 2.   Open quarter-wave section 3.   Shorted half-wave section 4.   Shorted quarter-wave section 1-11.   The range of operating frequencies is determined by which of the following wave-guide dimensions? 1.   The widest 2.   The longest 3.   The shortest 4.   The narrowest 1-12.   If frequency is decreased, what change, if any, will be required in the dimensions of the wave-guide bus bar? 1.   Decrease in dimensions 2.   Increase in dimensions 3.   None 1-13.   The cutoff frequency for a wave-guide is controlled by the physical dimensions of the wave-guide and is defined as the frequency at which two quarter- wavelengths are 1.   shorter than the "a" dimension 2.   shorter than the "b" dimension 3.   longer than the "b" dimension 4.   longer than the "a" dimension 1-14.   In practical applications, which of the following dimensions describes the wide dimension of the wave-guide at the operating frequency? 1.   0.1 wavelength 2.   0.2 wavelength 3.   0.5 wavelength 4.   0.7 wavelength 1-15.   Which of the following fields is/are present in wave guides? 1.   E field only 2.   H field only 3.   E and H fields 4.   Stationary field 1-16.   A difference in potential across a dielectric causes which of the following fields to develop? 1.   Electric field only 2.   Magnetic field only 3.   Electromagnetic field Figure 1A.—Electric field. IN ANSWERING QUESTION 1-17, REFER TO FIGURE 1A. 1-17.   What information is indicated by the number of arrows between the plates of the capacitor? 1.   The amount of capacitance 2.   The amount of current flow 3.   The strength of the electric field 4.   The strength of the magnetic field