Question

Which measured values could be used to determine the mass \[m\] of the electron?

Options

• Speed of light and colour of fluorescence

• Charge \[e\] and specific charge \[e/m\]

• Cathode material and ultraviolet light

• Gas pressure and type of glass

Answer 1

The electron’s mass \[m\] could be determined from its charge \[e\] and specific charge \[e/m\]. Thomson measured the specific charge, while Millikan precisely measured the charge.