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# Rutherford scattering experiment does not conclude the charge type? Watch

1. We can't depend on the observation on deciding whether it is positive or negative?
If yes, why? How can the same results be produced with negative charge?

The slight deflection would be downwards if it is negative and upwards if positive (alpha particles being fired) ... so how does this not confirm it?

Thanks
2. I don't understand the question. What is positive, what is negative?
3. (Original post by Daniel Atieh)
We can't depend on the observation on deciding whether it is positive or negative?
If yes, why? How can the same results be produced with negative charge?

The slight deflection would be downwards if it is negative and upwards if positive (alpha particles being fired) ... so how does this not confirm it?

Thanks
I think the conclusion of this experiment was that the nucleus of the atom is positively charged...
4. (Original post by mik1a)
I don't understand the question. What is positive, what is negative?
Yes

From the three deductions he came with: most went through without deflection, very few deflected 90 or more degs ...
we can say:1) atom is mostly empty space
2) large charge concentration at center
3) nucleus contains most mass

BUT can we say whether the charge is positive or negative? I read that it is not possible and even Rutherford wasn't sure from those observations, because the same observations would occur if it was negative. I can't understand how that is possible.

check this source also: https://www.aip.org/history/exhibits...cles-atom.html
(search for the word negative and it will take you to the paragraph)
5. (Original post by aamirac)
I think the conclusion of this experiment was that the nucleus of the atom is positively charged...
True, at the end of the story. But check my other reply please.
6. (Original post by Daniel Atieh)
Yes

From the three deductions he came with: most went through without deflection, very few deflected 90 or more degs ...
we can say:1) atom is mostly empty space
2) large charge concentration at center
3) nucleus contains most mass

BUT can we say whether the charge is positive or negative? I read that it is not possible and even Rutherford wasn't sure from those observations, because the same observations would occur if it was negative. I can't understand how that is possible.

check this source also: https://www.aip.org/history/exhibits...cles-atom.html
(search for the word negative and it will take you to the paragraph)
The link makes a good read. In my head, it always made sense to me that the nucleus was positively charged. But, as the page says, it could be that the nucleus is negatively charged and it 'slingshots' the alpha particles through angles greater than 90 degrees. My knowledge of physics is not enough to give you an answer, although I'm sure this was not the only test they used to show that the nucleus is positively charged. I'm sure that is probably just an oversimplification at GCSE or A level.
7. (Original post by Jpw1097)
The link makes a good read. In my head, it always made sense to me that the nucleus was positively charged. But, as the page says, it could be that the nucleus is negatively charged and it 'slingshots' the alpha particles through angles greater than 90 degrees. My knowledge of physics is not enough to give you an answer, although I'm sure this was not the only test they used to show that the nucleus is positively charged. I'm sure that is probably just an oversimplification at GCSE or A level.
thank you. i agree with you.

this is why he thought a negative nucleus works too:

8. (Original post by Daniel Atieh)
Yes

BUT can we say whether the charge is positive or negative? I read that it is not possible and even Rutherford wasn't sure from those observations, because the same observations would occur if it was negative. I can't understand how that is possible.

check this source also: https://www.aip.org/history/exhibits...cles-atom.html
(search for the word negative and it will take you to the paragraph)
If you read the text carefully, you can find this

Second, that number should be proportional to the square of the nuclear charge.

If the scattering result is proportional to the square of the nuclear charge, the squaring of negative nuclear charge would still give the same result.

In fact, we can see from Wikipedia or here, the final result for Rutherford scattering cross section or number of particles scattered at an angle show that the quantities (Z, e) that deal with charge are all raised to even power. I think this is the reason why the scattering result cannot conclude the whether the nuclear charge is positive or negative.

Hope these two cents make sense.

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Updated: September 13, 2016
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