The electron is known to have a radius no larger than 10-18 m. If actually produced by cir...

The electron is known to have a radius no larger than 10-18 m. If actually produced by circulating mass, its intrinsic angular momentum of roughly A would imply very high speed, even if all that mass were as far from the axis as possible, (a) Using simply rp (from |r X pj) for the angular momentum of a mass at radius r, obtain a rough value of p and show that it would imply highly relativistic speed, (b) At such speeds, E = ymc2 and p — ymc2 combine to give E  pc (just as for the speedy photon). How does this energy compare with the known internal energy of the electron?