Coulomb's Torsion Balance

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RRITESH KAKKAR

Joined Jun 29, 2010
2,829
The operational definition of a coulomb as the unit of electrical charge (in terms of force generated between point charges) was found to be equal to an excess or deficiency of about 6,250,000,000,000,000,000 electrons.
How the electron were counted?

The few practical applications of static electricity include xerographic printing, the electrostatic air filter, and the high voltage Van de Graaff generator.

source.
 
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WBahn

Joined Mar 31, 2012
25,910
Hello,
please explain how this device work
Torsion Balance
What is it that you need to have explained. Watch the video. Ask a specific question about what you saw in the video that you didn't understand.

Note that the video does a poor job toward the end of explaining how the quantitative value of the proportionality constant was arrived at. It also ignores the fact that it has units (namely Nm²/C²).
 

WBahn

Joined Mar 31, 2012
25,910
The operational definition of a coulomb as the unit of electrical charge (in terms of force generated between point charges) was found to be equal to an excess or deficiency of about 6,250,000,000,000,000,000 electrons.
How the electron were counted?
A number of different works came together to come up with these numbers.

For instance:

The basic form of the relationship can be determined via the Coulomb Torsion Balance experiment.

The ratio of the electron charge to the electron mass can be determined using the Helmholtz Coil experiment.

The fact that charge is quantized can be determined via the Millikan Oil Drop experiment.

The mass of an electron can be determined a few ways, such as with a Penning Trap.
 
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