(a) A particle of charge q moves in a circle of radius R at a constant speed v. To sustain the motion, you must, of course, provide a centripetal force mv2/R; what additional force (Fe) must you exert, in order to counteract the radiation reaction? [It’s easiest to express the answer in terms of the instantaneous velocity v.] What power (Pe) does this extra force deliver? Compare Pe with the power radiated (use the Larmor formula).
(b) Repeat part (a) for a particle in simple harmonic motion with amplitude A and angular frequency w (w (t) = A cos (wt) z). Explain the discrepancy.
(c) Consider the case of a particle in free fall (constant acceleration g). What is the radiation reaction force? What is the power radiated? Comment on these results.