# Homework Help: Stern-Gerlach experiment Problem

1. Mar 22, 2017

1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution
(a) : There is no interference. (b) : Interference

And i don't know how to approach (c), (d)

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2. Mar 22, 2017

### kuruman

Consider the wavefunctions in each case and the probability distribution at the screen that they entail.

3. Mar 22, 2017

(c) is just sum of l+> + l-> so the answer is same with (b), and i don't know if there is interference between l+> and l+>

4. Mar 22, 2017

### kuruman

In case (c), if you were to measure an electron's spin with another Stern-Gerlach machine, would you be able to tell through which slit the electron emerged?
What about if you did the same with an electron in case (d)?

5. Mar 22, 2017

I think , in case of (c) , there would be same amount of electron goes through each slit.

6. Mar 22, 2017

### kuruman

My question to you was not about amounts of electrons.
1. Suppose in case (c) you measured the spin of an electron to the right of the slits and you found it is "up". Would you be able to tell through which slit it went through?
2. Suppose in case (d) you measured the spin of an electron to the right of the slits and you found it is "up". Would you be able to tell through which slit it went through?

7. Mar 22, 2017

up spin go through upper slit

and in (d), up spin would be found in both slits

8. Mar 22, 2017

### kuruman

So in (c) you know through which slit the electrons have passed through, but in (d) you do not know. Can you put it together now in view of your answers in (a) and (b) and what you know about quantum interference?

9. Mar 22, 2017

I think in (c), upper slit ( + ) and lower slit ( - ) will interfere each other, and similarly, upper slit (+) and lower slit(+) will interfere each other in (d).
Or do i have to focus on that l+> and l-> are independent each other, so there are no interfere between l+> and l-> ??

10. Mar 23, 2017

### kuruman

11. Mar 24, 2017

I think i get it , this is my answer

But, is it right that i have to draw a half intensity in (c),(d) compared to (a),(b)

12. Mar 24, 2017

### kuruman

It's not a matter of intensity. If the electron flux is the same in all four cases, then what do you think should be the same in all four graphs?