How do u convert eV to joules again?

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how do u convert eV to joules again?
 

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  • #2
Integral
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some google key works "conversion factor" "ev" "power".

Why do you expect me or someone else to do your basic web search?
 
  • #3
Gonzolo
Googling "eV" gives it out directly :

1 electron volt = 1.60217646 × 10-19 Joules
 
  • #4
dextercioby
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Actually it's not basic web search.It would really be a shame to search the web for eV->J conversion factor...:yuck:

Daniel.
 
  • #5
Integral
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Why is that dex?
Not everyone has reference at hand. My goal was perhaps to lead him to a page full of conversion factors. Unfortunatly he may well find a calculator for doing conversions, and therefore never learn to do it on his own. But I think a web search is perfectly fine for this.
 
  • #6
dextercioby
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Depends on the OP's intentions.If he's aiming to become a physicist (which may vey well not be the case),then it's a shame not to know THIS SPECIFIC CONVERSION...
I'm not talking about-psi->torr->pascals,but eV->J...:wink:

Daniel.
 
  • #7
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Depends on the OP's intentions.If he's aiming to become a physicist (which may vey well not be the case),then it's a shame not to know THIS SPECIFIC CONVERSION...
I'm not talking about-psi->torr->pascals,but eV->J...
99.99% students in a highschool physics course are not going to be physicists, and,
99.9% students in a college physics course are not going to be physicists
 
  • #8
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vincentchan said:
99.99% students in a highschool physics course are not going to be physicists, and,
99.9% students in a college physics course are not going to be physicists
I don't think that's quite right.

What's the percentage of high school/college students who go on to do a Physics degree?
In mine it must have been about 5% or a bit under.
My definition of physicist is someone who qualifies to at least degree standard.
 
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what school are you in.... in my university.... out of 40000 student.... only 20 or so will graduate in physics this year!
 
  • #10
Gonzolo
I got to agree with vincentchan. A University I know has the same ratio. And that's not counting the significant amount of people who do not go to Univ. at all after school.

But back to the point, anyone who knows what an eV is should probably know the number 1.602E-19, at least 1.6E-19, but perhaps not the following decimals.
 
  • #11
dextercioby
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Since the second decimal is zero,it's useless to memorize 4 significative digits.An error made by neglecting that 4 decimal is much smaller than working with other constants,like \hbar...

Daniel.

P.S.I hope i made my point clear.
 
  • #12
rachmaninoff
What controversy!

I think the most useful way to know this is realize that an eV is by defintion the work done moving an electron through one volt - i.e., since 1C * 1V = 1J, and the charge of an electron is 1.602x10^-19J...
 
  • #13
dextercioby
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rachmaninoff said:
What controversy!

I think the most useful way to know this is realize that an eV is by defintion the work done moving an electron through one volt - i.e., since 1C * 1V = 1J, and the charge of an electron is 1.602x10^-19J...
That's not a correct "defintion" (sic).Please do not supply erroneous information...

Daniel.
 
  • #14
Galileo
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What's erroneous about it?
 
  • #15
dextercioby
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One "eV" is the energy that an electron gets when accelerated from rest by a potential difference of 1V.

Daniel.

P.S."moving an electron" sounds obscene.It's like moving furniture...:yuck:
 
  • #16
krab
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vincentchan said:
99.99% students in a highschool physics course are not going to be physicists, and,
99.9% students in a college physics course are not going to be physicists
Not true, and even if it were true, not relevant. Are you proposing that physics teaching standards can be lower because of the unlikelihood of producing physicists? Seems backwards to me.
 
  • #17
chroot
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dextercioby said:
One "eV" is the energy that an electron gets when accelerated from rest by a potential difference of 1V.
It doesn't matter whether or not the electron was initially at rest.

If you move an electron through a potential difference of 1V, the electron gains (or loses) 1 eV of kinetic energy.

- Warren
 
  • #18
Gonzolo
krab said:
Not true...
I'm getting off topic, but do you have any contradicting stats?
 
  • #19
dextercioby
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Does Vincentchan have contradicting stats for Krab's affirmation...?:bugeye:

Anyway,for the record,i think Krab is right.

Daniel.
 
  • #20
Gonzolo
vincentchan said:
what school are you in.... in my university.... out of 40000 student.... only 20 or so will graduate in physics this year!
gonzolo said:
A University I know has the same ratio. And that's not counting the significant amount of people who do not go to Univ. at all after school.
2 stats to 0 stats. Eager for more numbers, and completely open minded.
 
  • #21
krab
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vincentchan said:
what school are you in.... in my university.... out of 40000 student.... only 20 or so will graduate in physics this year!
Since I am being pushed...

This stat is not relevant to the original claim you made...

vincentchan said:
99.9% students in a college physics course are not going to be physicists
...says one in a 1000 students in college physics become physicists. So the question is : of the 20 who graduated, how many became physicists?
 
  • #22
SpaceTiger
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...says one in a 1000 students in college physics become physicists. So the question is : of the 20 who graduated, how many became physicists?
I assumed he was talking about the intro courses. The vast majority of students in those courses aren't physics majors. At PSU, it probably made up something like 1% of the class. For his statement to be correct, you would then need 1 in 10 of those students to become physicists. Probably an underestimate, but not wildly off.
 
  • #23
Andrew Mason
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dextercioby said:
One "eV" is the energy that an electron gets when accelerated from rest by a potential difference of 1V.
Or the energy lost by an already moving electron in passing through a potential difference of +1 volt; which is the work done by an electron moving through a potential of 1 volt, and that is pretty much what rachmaninoff said.

AM
 
  • #24
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Did I contracdict myself ?
 
  • #25
dextercioby
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No,you didn't just that the number that u offered was way off...Anyway,even if,by absurd,one of the #s posted is correct,i think it's fair to say that becoming a physicist requires a lotta work and very few are willing to do it.

From my perspective,this thread is dead,too.

Daniel.
 

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