# How did they measure the charge of electron

by Boody
Tags: charge, electron, measure
 P: 4 I know that a charge is discribed in terms of coulombs. But how did they know that an electron has a charge of 1.60217646 × 10-19 coulomb ? by the way , what is a coulomb exactly ? and how did they found or discribed its quantity ? I would like the answer to be in details please . Thanks
 P: 1,781 Look up the Millikan oil drop experiment. A coulomb is exactly that amount of charge which results from a current of one Ampere flowing for one second.
 P: 4 you said it is " the amount of charge which results from a current of one Ampere flowing for one second " ,, what is Ampere ? and how would we find it ? ( suppose we want to calculate the charge and the magnitude of the charge is not given)
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Thanks
P: 25,588

## How did they measure the charge of electron

Hi Boody! Welcome to PF!
 Quote by Boody … what is Ampere ? and how would we find it ?
The ampere (small "a" ) is defined in terms of ordinary mechanical units.

From the PF Library
the amp is that current which in a pair of wires a metre apart would produce a force between them of 2 10-7 N/m
 P: 4 mmmm, I see Thanks :)

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