Problem 4.217

A charged particle moves along the $y$ axis according to the law $y=a \cos \omega t,$ and the point of observation $P$ is located on the $x$ axis at a distance $l$ from the particle $(l \gg a)$. Find the ratio of electromagnetic radiation flow densities $S_{1} / S_{2}$ at the point $P$ at the moments when the coordinate of the particle $y_{1}=0$ and $y_{2}=a$. Calculate that ratio if $\omega=3.3 \cdot 10^{6} \mathrm{~s}^{-1}$ and $l=190 \mathrm{~m}$.