A plane electromagnetic wave travels in vacuum along z – direction. If the frequency of the wave is 40 MHz then its wavelength is:

5 m 7.5 m 8.5 m 10 m

7.5 m

Wavelength, $\lambda=\frac{c}{v}=\frac{3 × 10^8 ms^{-1}}{40 \times 10^6 s^{-1}}$ = 7.5 m