A single electron with de Broglie wavelength λ passes through a slit of width d=2λ.The electron can strike a fluoroscent screen.What will be observed on the screen? (a)a diffraction pattern (b)a single flash as if the electron had moved in a straight line through the slit. (c)a single flash that could occur anywhere on the screen. (d)a single flash that would most likely occur where a corresponding diffraction pattern would have the highest intensity. (a)clearly wrong (b)wrong as electron must have interacted with the slit (c)It seems incorrect as it means that the flash can occur even at a remote end of the screen also where the electron may not possily reach... (d)looks correct to me... Please let me know if I am correct
Hmm I have next to no knowledge about this, but why must the electron have interacted with the slit ?
In QM we must see electron as a object with wave particle duality.Quantum systems interact with instruments and therefore, gets disturbed.For this reason, there is always uncertainty in measurement inherently.Even if with so-called ideal instruments...
Hmm yes but if the amplitude of the particle is smaller than the width of the slit I don't see why the particle should interact with the slit. Would you say the same thing if the slit was 2 meters wide ?
Well, this really depends on the quantum state of the electron. If it passes through the [single slit], normally it will spread out over space as a wave. This means that the electron doesn't ''interfere'' with itself, so it reaches the screen in a flood of waves. If both slits are open, then the electron would interfere with itself, and less particle-like dots are left. But if one slit is open, and the particle is observed, the electron would collapse, and less marks would hit the screen, because then it doesn't travel through spacetime as a wave of probability... This has been proven.
Reiku, we are talking about a single electron. Care to explain how a single electron can spread out ?
That's ok. It's just that the concept is misunderstood here. Yeh... it does spread out even with one slit open. That is why, if one slit is only ever open, then the particle can spread out, and no interference can occur.
They make a point of the slit being larger than the electron's wavelength. The "diffraction probability distribution" is a result of interference, which requires at least two slits.
I still don't understand how a single electron can spread out.. maybe I'm dumb Please Register or Log in to view the hidden image!
It can't and it dosen't. An electron is a particle. It has a wave-like property that is best demonstrated by quantum electrodynamics (QED). Your best bet would be to read Feynmans "QED: The Strange Theory of Light and Matter". It's fully accessible to laymen. An easy and fun read.
Thanks Luminal Please Register or Log in to view the hidden image! So it can't spread out.. then in my laymen's view it must be answer b, right ?
No, there's also single-slit diffraction: http://en.wikipedia.org/wiki/Diffraction#Single-slit_diffraction
Unless someone has a better understanding of it than what I've seen here, b is correct. The question states that the slit is twice as wide as the wavelength of the electron, therefore (in my understanding) there is no reason for the electron to interact with the slit. If it dosen't interact with the slit, the electron will strike, like the particle it is, exactly where it's aimed.
Hmmm... Check quadraphonics wiki link. Not sure how it applies, but makes me start to question some things...
No. I mean quadraphonics the member. His link to electron diffraction: http://en.wikipedia.org/wiki/Diffraction#Single-slit_diffraction
Yes, but those are many particles. Here we are talking about a single electron. In my understanding electron don't just fissure outside of a particle accelerator.
Nor have they ever been seen to fissure inside of a particle accelerator, for that matter. The important thing here, though, is that the electron acts like a wave, so it can "interfere with itself." Similarly, electrons in the two-slit experiment cluster around a diffraction pattern, even when only one is fired at a time. I think the key to this problem is figuring out what is meant by the phrase "corresponding diffraction pattern" in option d).
