Converting eV to V: Debunking the Myth and Simplifying the Process

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Discussion Overview

The discussion revolves around the conversion between electron volts (eV) and volts (V), exploring the relationship between electric potential and energy. Participants examine whether it is valid to convert these two units and the implications of such a conversion in different contexts, including the behavior of charged and neutral particles.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Mathematical reasoning

Main Points Raised

  • Some participants argue that since eV = Q[SUB]electron[SUP] * V, dividing eV by the charge of the electron could yield a voltage (V).
  • Others contend that V and eV represent fundamentally different concepts, with V being electric potential and eV being energy, suggesting that a direct conversion is not appropriate.
  • One participant points out that while you can derive a voltage from energy when the charge is known, this does not apply universally since charges can vary (e.g., alpha particles have a charge of +2e).
  • Another participant highlights that neutral particles, like neutrons or gamma rays, do not have a charge, complicating the use of eV in defining their energy in terms of voltage.
  • Concerns are raised about attempting to equate a physical relationship with a unit of measurement, suggesting that such comparisons can lead to nonsensical conclusions.

Areas of Agreement / Disagreement

Participants express differing views on the validity of converting eV to V, with no consensus reached. Some support the idea of conversion under specific conditions, while others firmly reject the notion based on the fundamental differences between the units.

Contextual Notes

Participants note that the conversion depends on the charge involved and that the relationship is not straightforward due to the nature of different particles. The discussion also highlights the limitations of applying algebraic equations to physical relationships without careful consideration of the units involved.

robwashere
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I've done some research on this, but some people say that you cannot convert these two things. They say that V is electric potential, and eV is energy.

What I was thinking was since eV = Qelectron * V, can't you just divide eV by charge of electron to get V?

Sorry if this is a dumb question
 
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Umm...how to explain this.
OK, so put it this way. I can convert between meter and foot because they're both distance. Thus, the conversion values are equivalent.
But what you're saying is to convert between two things that have, effectively, little in common. in a conversion, the values must be equivalent. This isn't the case with what you have here.
 
robwashere said:
I've done some research on this, but some people say that you cannot convert these two things. They say that V is electric potential, and eV is energy.

What I was thinking was since eV = Qelectron * V, can't you just divide eV by charge of electron to get V?


Sort of. If you have an energy expressed in electron volts, and you know the charge, you get a voltage (a potential difference) when you divide the energy by the charge. Charges are not always equal to the elementary electron charge. For example, an alpha particle is like a helium nucleus, so it has a charge of +2e. So to accelerate an alpha particle to an energy of 1 MeV, you have to have a potential of 500,000 volts.
 
Neutral particles such as neutrons or gamma rays are often described using electron-volts to define their energy - there is no charge.
 
robwashere said:
I've done some research on this, but some people say that you cannot convert these two things. They say that V is electric potential, and eV is energy.

What I was thinking was since eV = Qelectron * V, can't you just divide eV by charge of electron to get V?

Sorry if this is a dumb question


You're trying to setup an algebraic equation with a unit on one side and a physical relationship on the other, which is not possible.

It would be like saying that meter = vt + {{1}\over{2}}at^2, which is clearly nonsensical.
 

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