Question

Energy radiated by accelerating electron

Answer 1

An electromagnetic wave, as its name implies, consists of alternating electric and magnetic fields, oriented at 90 degrees to each other, moving at the speed of light. These alternating fields sustain themselves because electricity (moving electric charges) generates a magnetic field, and a changing magnetic field generates an electric field. 

Answer 2

When any charged particle like electrons, protons or ions accelerates, it radiates away in the form of "electromagnetic force".