A charged particle moves uniformly with velocity v along a circle of radius R in the plane xy (Fig. 4.40). An observer is located on the x axis at a point P which is removed from the centre of the circle by a distance much exceeding R. Find:
(a) The relationship between the observed values of the y projection of the particle's acceleration and the y coordinate of the particle;
(b) The ratio of electromagnetic radiation flow densities S1/S2 at the point P at the moments of time when the particle moves, from the standpoint of the observer P, toward him and away from him, as shown in the figure.

P 2