A transmission line of 50$$\Omega $$ characteristic impedance is terminated with a 100 $$\Omega $$ resistance. The minimum impedance measured on the line is equal to

A $${\lambda \over 2}$$ section of a 600 $$\Omega $$ transmission line, short ciruited at one end and open circuited at the other end, is shown in Fig. A 100 V / 75 $$\Omega $$ generator is connected at the mid point of the section as shown in the Fig. Find the voltage at the open-ciruited end of the line.

A uniform plane wave is normally incident from air on an infinitely thick magnetic material with relative permeability 100 and relative permittivity 4 (sec in Fig.). The wave has an electric field of 1 V/meter (rms). Find the average Poynting vector inside the material.

A rectangular air-filled waveguide has a cross section of $$4\,cm\,\, \times \,\,10cm$$. The minimum frequency which can propagate in the waveguide is