The electric field amplitude of an electromagnetic wave is $100 N C^{-1}$ and its frequency is 50 MHz. What is the magnitude of wave vector $(k)$. (given speed of electromagnetic wave is $3 \times 10^8 ms^{-1}$)

$\frac{\pi}{3}$

The correct answer is Option (2) → $\frac{\pi}{3}$

The magnitude of the Wave vector (k) for an electromagnetic wave is related to its wavelength (λ) by -

$K=\frac{2π}{λ}=\frac{2πv}{C}$  $[λ=\frac{c}{v}]$

$∴K=\frac{2π×50×10^6}{3×10^8}$  [v = frequency = $50×10^6s^{-1}$ given]

$=\frac{\pi}{3}$