The stem means: accelerated charged particles, under the action of electric and magnetic fields, emit energy in the form of ______.

According to Maxwell's theory, a charge at rest produces only an electric field and a uniformly moving charge also produces a magnetic field, but an accelerated charge produces oscillating electric and magnetic fields that propagate as electromagnetic waves.

The energy carried away by these waves is called electromagnetic radiation; examples include radio waves from oscillating charges in antennas and X-rays from decelerating electrons. Electromagnetic induction, by contrast, is the generation of an EMF by a changing magnetic flux.

Hence, the answer is electromagnetic radiation.