The mass of the proton was determined in a similar way to how the mass of atoms are
measured.
The particle, whose mass is being determined, is accelerated through an electric field, the
particle then passes through a perpendicular magnetic field which deflects the particle (particle must be charged, a proton or an ion for example, for it to deflect). The
angle by which it deflects is dependent on the mass of the particle. The mass of the particle can be determined by using the following formula:
Centripetal Force = Force due to magnetic field(B)
(mv^{2})/r = Bqv
(where m = mass of particle, v = velocity of particle, r= radius of deflected path, B =
magnetic field strength, q = charge of particle)
Answered by: Simon Hooks, Physics A-Level Student, Gosport, UK
'A theory with mathematical beauty is more likely to be correct than an ugly one that fits some experimental data. God is a mathematician of a very high order, and He used very advanced mathematics in constructing the universe.'