GATE Question Of The Day - Electromagnetics

A transmission line of characteristic impedance 50W is terminated by a 50 W load. When excited by a sinusoidal voltage source at 10GHz, the phase difference between two points spaced 2mm apart on the line is found to be p/4 radians. The phase velocity of the wave along the line is

(A)  0.8 ´ 10⁸ m / s

(B) 1.2 ´ 10⁸ m / s

(C) 1.6 ´ 10⁸ m / s

(D)  3 ´ 10⁸ m / s