Converting eV to Joules vs eV to V

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Homework Help Overview

The discussion revolves around the conversion between electron volts (eV) and joules (J), as well as the relationship between electron volts and volts (V). Participants are examining the definitions and implications of these units in the context of energy and potential difference.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Some participants confirm the conversion of 1 eV to 1.6e-19 J while questioning the validity of stating that 1 V equals 1.6e-19 eV. They explore the definition of an electron volt and its relationship to voltage, discussing the implications of moving an electron across a potential difference.

Discussion Status

Participants are actively engaging with the definitions and relationships between the units, with some providing clarifications based on external sources. There is a recognition of the need to understand how potential difference relates to kinetic energy and the conversion between units, though no consensus has been reached on the interpretations being explored.

Contextual Notes

Participants are navigating potential confusion regarding the definitions and conversions of energy and voltage, particularly in the context of calculating potential differences related to kinetic energy and wavelength. There is mention of needing to clarify the proper units and conversions involved in their calculations.

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Homework Statement


Is this true?

Homework Equations


1 eV = 1.6e-19 J
1 V = 1.6e-19 eV

The Attempt at a Solution



I did a bit of googling and it just seems strange.
eV multiplied by elementary charge = Joules
ev divided by elementary charge = Volts
 
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grandpa2390 said:

Homework Statement


Is this true?

Homework Equations


1 eV = 1.6e-19 J
1 V = 1.6e-19 eV

The Attempt at a Solution



I did a bit of googling and it just seems strange.
This is correct: 1 eV = 1.6e-19 J

This is not correct: 1 V = 1.6e-19 eV

http://en.wikipedia.org/wiki/Electronvolt

An electron volt is a certain amount of energy, not voltage. By definition, 1 electron volt is the amount of energy it takes to move 1 electron across a potential difference of 1 volt.
 
SteamKing said:
This is correct: 1 eV = 1.6e-19 J

This is not correct: 1 V = 1.6e-19 eV

http://en.wikipedia.org/wiki/Electronvolt

An electron volt is a certain amount of energy, not voltage. By definition, 1 electron volt is the amount of energy it takes to move 1 electron across a potential difference of 1 volt.

By definition, it is the amount of energy gained (or lost) by the charge of a single electron moved across an electric potential difference of one volt. Thus it is 1 volt (1 joule per coulomb, 1 J/C) multiplied by the elementary charge (e, or 1.602176565(35)×10−19 C).
this is from the wikipedia page. what does this mean then if it is not saying one electron-volt is equal 1.6e-19 C * 1 Volt

based on that, 1 ev / 1.6e-19 C = 1 Volt, right? or am I missing something?

edit: or was issue not with the conversion, but with the units in my question?
1 Volt = 1.6e-19 C*eV rather than what I wrote: 1.6e-19 eV

if that be the case, my apologies, I was being hasty with my concern more for the conversion factor than the proper units.
 
SteamKing said:
This is correct: 1 eV = 1.6e-19 J

This is not correct: 1 V = 1.6e-19 eV

http://en.wikipedia.org/wiki/Electronvolt

An electron volt is a certain amount of energy, not voltage. By definition, 1 electron volt is the amount of energy it takes to move 1 electron across a potential difference of 1 volt.
The reason I am asking is because I have to calculate the the potential difference an electron would have to be accelerated through to give it a certain wavelength.
so far I have the potential difference = to the kinetic energy divided by 1.6e-19. but that would give a potential difference in electron volts. to convert to volts, shouldn't i divide again by 1.6e-19 Coulombs?

edit: I don't know I am reading something that says an electron gains 1 ev per 1 volt of potential difference. so maybe they are equal for one electron. this is all very confusing.
 
Last edited:
grandpa2390 said:
By definition, it is the amount of energy gained (or lost) by the charge of a single electron moved across an electric potential difference of one volt. Thus it is 1 volt (1 joule per coulomb, 1 J/C) multiplied by the elementary charge (e, or 1.602176565(35)×10−19 C).
this is from the wikipedia page. what does this mean then if it is not saying one electron-volt is equal 1.6e-19 C * 1 Volt

based on that, 1 ev / 1.6e-19 C = 1 Volt, right? or am I missing something?
grandpa2390 said:
The reason I am asking is because I have to calculate the the potential difference an electron would have to be accelerated through to give it a certain wavelength.
so far I have the potential difference = to the kinetic energy divided by 1.6e-19. but that would give a potential difference in electron volts. to convert to volts, shouldn't i divide again by 1.6e-19 Coulombs?

edit: I don't know I am reading something that says an electron gains 1 ev per 1 volt of potential difference. so maybe they are equal for one electron. this is all very confusing.

1 electron volt already assumes a potential difference of 1 volt. Since 1 eV ≈ 1.602×10-19 joules, then divide the kinetic energy in joules by 1.602×10-19 to convert the KE of the electron into electron volts. This number will also be the voltage required to accelerate 1 electron such that it has that wavelength.
 
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