You are Here: Home

# Electric Potential well

Announcements Posted on
Uni student? You could win a Samsung Galaxy S7 or £500 of travel vouchers by taking this quick survey 05-05-2016
Talking about ISA/EMPA specifics is against our guidelines - read more here 28-04-2016
1. Question:

I'm facing a problem in part (b)(i). When using the formula , shouldn't we take the value of r to be 0.52x10-10 m? Mark scheme takes the value of r to be the diameter of circle, i.e 1.04x10-10 m.

Also, why doesn't reading the value of potential from the graph give the correct answer?
2. ..I don't know why the mark scheme would say that, since clearly the radius is the distance between the electron and nucleus. How weird . I would have thought your answer is correct.
3. 1) The value of V should be read directly from the graph at r = 0.52 x 10-10 m if it's the diameter that is given as 1.04x10-10
2) The field strength at that point is the (negative) potential gradient at that point.
4. (Original post by Stonebridge)
1) The value of V should be read directly from the graph at r = 0.52 x 10-10 m if it's the diameter that is given as 1.04x10-10
2) The field strength at that point is the (negative) potential gradient at that point.
Right. But why can't we apply the formula for Potential in this question?
5. (Original post by Zishi)
Right. But why can't we apply the formula for Potential in this question?
Why do you need to?
6. (Original post by Stonebridge)
Why do you need to?
I don't need to, but just wondering that it should also give the same answer as given by the graph. . .
7. If you plug in the correct values for the other quantities it should.
The graph itself would have been plotted from the equation.
If it doesn't give the same value that would be odd, but it is irrelevant in (what I can see of) this question as there is no need to use the formula.
You are expected to use the graph.
8. (Original post by Stonebridge)
If you plug in the correct values for the other quantities it should.
The graph itself would have been plotted from the equation.
If it doesn't give the same value that would be odd, but it is irrelevant in (what I can see of) this question as there is no need to use the formula.
You are expected to use the graph.
Hmm. Anyway, it's giving a different answer. Many thanks.
9. (Original post by Zishi)
Question:

I'm facing a problem in part (b)(i). When using the formula , shouldn't we take the value of r to be 0.52x10-10 m? Mark scheme takes the value of r to be the diameter of circle, i.e 1.04x10-10 m.

Also, why doesn't reading the value of potential from the graph give the correct answer?
Is the answer to the 3c. -8.33x10^10 ?
10. (Original post by bmqib)
Is the answer to the 3c. -8.33x10^10 ?
Yeah.

## Register

Thanks for posting! You just need to create an account in order to submit the post
1. this can't be left blank
2. this can't be left blank
3. this can't be left blank

6 characters or longer with both numbers and letters is safer

4. this can't be left empty
1. Oops, you need to agree to our Ts&Cs to register

Updated: April 25, 2012
TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Today on TSR

Don't be late