Question

how mass of proton and electron is calculated.

Answer 1

The electron rest mass in kilograms is calculated from the definition of the Rydberg constant R∞:

R_{\infty} = \frac{m_{\rm e}c\alpha^2}{2h} \Rightarrow m_{\rm e} = \frac{2R_{\infty}h}{c\alpha^2}

Answer 2

In quantum chromodynamics, the modern theory of the nuclear force, most of the mass of the proton and the neutron is explained by special relativity. The mass of the proton is about 80–100 times greater than the sum of the rest masses of the quarks that make it up, while the gluons have zero rest mass. The extra energy of the quarks and gluons in a region within a proton, as compared to the rest energy of the quarks alone in the QCD vacuum, accounts for almost 99% of the mass

Answer 3

First e/m ratio of the electron was calculated by J.J Thomson. It could be done easily by simple experiments based on deflections of electron in electric and magnetic fields. Then Millikan performed an experiment to find 'e'. Hence ,the calculation of 'm', mass of electron became possible.

e is same for electron as well as proton. We could perform a similar defection experiment for proton and find its e/m ratio. And then putting the value of e, find its mass.