$(a)$ $A$ particular transmitter of Aakashvani broadcasts at $420.5\, m$ wavelength. Given the speed of radio waves $3 \times 10^{8}\, m s^{-1}$. Calculate the frequency at which the radio station broadcasts its programme.
$(b)$ What is the direction of oscillations of the medium particles through which a
$(i)$ transverse wave is propagating?
$(ii)$ longitudinal wave is propagating?

(A-D) Given: $\lambda = 420.5\, m$,$V = 3 \times 10^{8}\, m s^{-1}$.
Using the wave equation $V = \nu \lambda$,the frequency $\nu$ is given by $\nu = V / \lambda$.
Substituting the values: $\nu = (3 \times 10^{8}) / 420.5 \approx 7.13 \times 10^{5}\, Hz$.
$(b)$ $(i)$ In a transverse wave,the particles of the medium oscillate perpendicular to the direction of wave propagation.
$(ii)$ In a longitudinal wave,the particles of the medium oscillate parallel to the direction of wave propagation.