Exploring the Confusing Units in Physics: Electron Volt & Volt

In summary, the conversation discusses the concept of electron volts and volts in relation to energy and potential difference. It is clarified that the eV is its own unit of energy and is not equivalent to the joule. The conversation also touches on the potential energy gained by a charged particle when traversing a potential difference of one volt. The topic of nuclear reactions and energy yield is briefly mentioned. The conclusion is reached that the eV is a useful unit for measuring energy in relation to electric potential.
  • #1
Stephanus
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Dear PF Forum,
I'm interested in the future. How mankind will benefit from fusion power. But there are some terms that I don't understand.
Electron Volt.
https://en.wikipedia.org/wiki/Electronvolt
In physics, the electronvolt[1][2] (symbol eV; also written electron volt) is a unit of energy equal to approximately 160 zeptojoules...

Volt
https://en.wikipedia.org/wiki/Volt
Voltage, electric potential difference, electric pressure or electric tension (denoted ∆V or ∆U) is the difference in electric potential energy ...

Perhaps this yes/no question will confirm my confusion.
1. Electron Volt Unit is Joule?
2. Volt unit is Volt? (of course)
3. Watt * Second = Electron Volt?
4. Watt / Ampere = Volt (this I think I have known long ago)?
The names are confusing me.
Thanks
 
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  • #2
Stephanus said:
1. Electron Volt Unit is Joule?
No. The eV is its own unit. The eV is a unit of energy and the J is a unit of energy, so you can convert between J and eV if you like, but they are separate units.

Stephanus said:
3. Watt * Second = Electron Volt?
No, 1 W s = 1 J

Stephanus said:
4. Watt / Ampere = Volt (this I think I have known long ago)?
Yes.
 
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  • #3
It is like light years: not a unit of time but of distance.

One eV is the energy that an elementary charge gets when it traverses a potential difference of one volt.
 
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  • #4
Thanks Dale for the reply.
Just curious, how many energy yield if we do P+P reaction. Although our technology is not adequate right now. Even the D+T heavily researched reaction still haven't produced a significant result.
DaleSpam said:
Stephanus said:
3. Watt * Second = Electron Volt?
No, 1 W s = 1 J
In physics, the electronvolt is a unit of energy equal to approximately 160 zeptojoules (symbol zJ) or 1.6×10−19 joules...

So, I think...
3. 1.6x10-19 Watt * second = One Electro Volt
or
One Watt applied for 1.6x10-19 second = One Electro Volt

http://hyperphysics.phy-astr.gsu.edu/hbase/astro/procyc.html
And if P+P reaction gives approximately 25 MEv, then...
1 Kg Hydrogen +1 Kg Hydrogen will produce 25x106 x 1.6 10-19 x 6 x 1026 (number of Protons in 1 KG) = 2.4 x 1013 joules?
I'm sorry, this should belong to Nuclear Physics question I think. But I only want to know if my understanding of this Electron Volt is correct.

Thanks
[EDIT: 1 Kg H + 1 Kg H -> 2.4 x 1015 joules]
 
  • #5
PietKuip said:
It is like light years: not a unit of time but of distance.

One eV is the energy that an elementary charge gets when it traverses a potential difference of one volt.
Yeah, I know a long time that light year is not a unit of TIME, even though some of my friends don't understand that and don't even hear about light year.
So this Ev is not a unit of potential charge but a unit of energy.
Okayyy, thanks.
 
  • #6
Stephanus said:
So, I think...
3. 1.6x10-19 Watt * second = One Electro Volt
or
One Watt applied for 1.6x10-19 second = One Electro Volt
Yes.
 
  • #7
PietKuip said:
One eV is the energy that an elementary charge gets when it traverses a potential difference of one volt.
That needs to be repeated because it's the whole justification for using the eV. The fact is that all charged particles in experiments (electrons, ions) are accelerated using Electric Potentials and the energy they gain is always because of the same basic charge (e). It's an obvious unit to use when you have electrons and Volts. It confuses everyone - just once - and then it's a very friendly thing to use.
 

1. What is the difference between an electron volt and a volt?

An electron volt (eV) is a unit of energy, specifically the amount of energy that an electron gains when it moves through a potential difference of one volt. On the other hand, a volt (V) is a unit of electric potential, which is the amount of potential energy per unit charge. In simpler terms, an eV measures the energy of an individual particle, while a volt measures the strength of an electric field.

2. Why are these units often confused with each other?

Electron volts and volts are often confused because both units involve the concept of energy and are used in the field of physics. Additionally, they have similar symbols (eV and V) which can contribute to the confusion.

3. How are these units related to each other?

Electron volts and volts are related through the fundamental equation E = qV, where E represents energy, q represents charge, and V represents voltage. This equation shows that energy and voltage are directly proportional, meaning that an increase in voltage will result in an increase in energy.

4. Can these units be converted into each other?

Yes, electron volts and volts can be converted into each other using the conversion factor 1 eV = 1.602 x 10^-19 V. This means that 1 electron volt is equal to 1.602 x 10^-19 volts.

5. In what situations is it more appropriate to use electron volts instead of volts?

Electron volts are often used in the field of atomic and nuclear physics, where the energy of individual particles is of interest. It is also commonly used in describing the energy levels of atoms and molecules. On the other hand, volts are typically used in practical applications such as electrical circuits and power systems.

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