A plane electromagnetic wave of frequency 40 MHz travels in free space in the X-direction. At some point and at some instant, the electric field $\vec{E}$ has its maximum value of 750 N/C in Y-direction.
The wavelength of the wave is:
Answer & explanation
Correct answer: option 3
$\lambda = \frac{c}{\nu} = \frac{3\times 10^8}{4\times 10^7} = 7.5 m$