# Electric fields

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#1
If I passed an electron through potential difference of 100 volts, would the electron gain 100eV of energy and therefore 1.6 x 10^-17J?
Just want to check if my understanding is right.
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5 years ago
#2
Correct. It is because a charged particle in an electric field has associated with it a potential energy due to the field. If it is displaced a distance r away from the central charge, it's potential has changed. Between the two points is a potential difference. Since the energy gained or lost is the potential difference multiplied by the charge, then an electron of charge 1.6E-19C that accelerated through a pd of V volts has gained/lost 1.6E-19C * V joules of energy. And an eV is just the work done in accelerating an electron through a pd of 1V.
0
5 years ago
#3
(Original post by Zevo)
If I passed an electron through potential difference of 100 volts, would the electron gain 100eV of energy and therefore 1.6 x 10^-17J?
Just want to check if my understanding is right.
By definition Voltage is defined as Joules per Coulomb of charge.

So an electron accelerated across a potential difference of 100V will then acquire 100eV worth of energy. E=qV
0
5 years ago
#4
(Original post by uberteknik)
By definition Voltage is defined as Joules per Coulomb of charge.

So an electron accelerated across a potential difference of 100V will then acquire 100eV worth of momentum.
100eV is not a measurement of momentum. The electron does acquire momentum on the process of acceleration, eV and J are measurements of energy.
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5 years ago
#5
(Original post by Protoxylic)
100eV is not a measurement of momentum. The electron does acquire momentum on the process of acceleration, eV and J are measurements of energy.
Corrected. I left out the /c part.

Wiki entry:

"In high-energy physics, the electron volt is often used as a unit of momentum. A potential difference of 1 volt causes an electron to gain an amount of energy (i.e., 1 eV). This gives rise to usage of eV (and keV, MeV, GeV or TeV) as units of momentum, for the energy supplied results in acceleration of the particle.

The dimensions of momentum units are LT−1M. The dimensions of energy units are L2T−2M. Then, dividing the units of energy (such as eV) by a fundamental constant that has units of velocity (LT−1), facilitates the required conversion of using energy units to describe momentum. In the field of high-energy particle physics, the fundamental velocity unit is the speed of light in vacuum c. Thus, dividing energy in eV by the speed of light, one can describe the momentum of an electron in units of eV/c."
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