Question

Who determined the charge of an electron

Answer 1

Experimentally opened an electron in 1897 by Joseph John Thomson in experiments with vacuum tubes.

In 1909, Robert Andrews Millikan, in experiments with the fall of oil droplets, demonstrated that an electric charge can have only discrete values multiplied by a certain elemental charge and measured the value of this charge.

Links:

Thomson, J.J. (1897). "Cathode Rays"

Millikan, R. A. (1913). "On the Elementary Electric charge and the Avogadro Constant".

Franklin, A. (1997). "Millikan's Oil-Drop Experiments".