A helium-3 nucleus (3He2+^3\text{He}^{2+}3He2+) of mass 3m and charge +2e+2e+2e enters a uniform magnetic field of magnetic flux density B B\,B at right angles to the field. The nucleus moves with a non-relativistic speed v v\,v in a circular path of radius rrr.
What is the number of complete revolutions made by the helium-3 nucleus in one second?
Be3πm\frac{Be}{3\pi m}3πmBe
2Be3πm\frac{2Be}{3\pi m}3πm2Be
3πmBe\frac{3\pi m}{Be}Be3πm
Beπm\frac{Be}{\pi m}πmBe