Postby **twistor** » Wed May 23, 2007 9:26 pm

I think there is another, simpler way of thinking about this problem. Recall that the magnitude of the field is proportional to the perpendicular component of the acceleration (as seen from the observation point) when you're speaking of electric dipole radiation.

Now, in this means when your observation point P is on the x-axis you will not see any field because there is no perpendicular component to the acceleration as viewed from this point. Similarly, when you view the accelerating particle at 90 degrees offset from the x-axis the total acceleration is the same as the perpendicular component. Therefore the radiation has a maximum at 90 degrees from the x-axis and the correct answer is C, as danty indicated.