Question #14fe2

2 Answers
Nov 13, 2017

We know it’s has the opposite charge to a proton, and it is essentially a convention that decides the electron is negative.


We know electrons are emitted from cathodes in low pressure gases, but that doesn’t actually provide much help, since a cathode is just an electrode with an excess of ‘negative’ charges.

For a large chunk of physics (excepting electromagnetism and a couple of other areas) it actually makes no difference whether the charge is considered to be positive or negative, just that it is unitary.

Nov 16, 2017

"1" actually means #1.60217662 × 10^"-19"# coulombs.


This is because the SI electric charge unit, the coulomb, was defined as the amount of electric charge flowed in one second at one ampere of intensity of electric current.

The value of the elementary electric charge of one electron was firstly determined in the 1909 famous oil drop experiment by American physicist Robert Andrew Millikan.

At that time the unit of electric charge was "electrostatic unit" or "statcoulomb" (a CGS - ESU unit) and the electron charge was #4.774 × 10^"-10"# electrostatic units.
One statcoulomb equals #3.3356 × 10^"-10"# coulombs.

About the minus sing, that was after Benjamin Franklin. He believed the two opposite charges were actually due to a single kind of fluid, whose excess would determine " a positive" or vitreous electric state, whereas a depletion would give a "negative" or "resinous" type electric state.

Later on, it was demonstrated rubbing resins, yielding the "resinous" or negative electric state, entailed an easy transfer of particles with that "lack of fluid". In other words negative electric state was caused by a transfer of "negative" particles. Those easily movable particles were the electrons. That was the -historical - reason why the electrons are told to have a "negative charge".

Actually, Franklin's electric fluid does not really exist. Electric charge can be neither observed nor measured as independent by or as something "external" to the particles. Physicists view electric charge as a "state" of particles, not as something "carried" by them.