(c) \(\frac{\pi}2\) radians
Electrical path length = \(\beta\)l radians
velocity v = \(\frac{1}{\sqrt{LC}}\) = \(\frac1{\sqrt{10\times10^{-6}\times40\times10^{-12}}}\)
\(\beta\)l = \(\frac{2\pi}{\lambda}\) x l
= \(\frac{2\pi}{2}\) x \(\frac{50}{100}\)
\(\frac{\pi}2\) radians