Question

Explain Why do we calculate the e/m ratio of an electron?

Answer 1

Charge-to-mass ration plays important role in electron microscopy, spectroscopy, etc. Two particles with the same charge-to-mass ratio move in the same path in a vacuum, when subjected to the same electric and magnetic fields. Thus in some apparatus, like mass spectrometer or cloud chamber the charge and mass cannot be separately measured —only their ratio.