Why a two-slit experiment with electrons is evidence electrons are waves?

[nukeman]

Homework Statement

I'm just trying to prepare a study pack for my final. I am curious about something I have been reading over in my textbook. Can someone please explain this for me?

"Be able to explain why a two-slit experiment with electrons is evidence that electrons are waves"

??

Homework Equations

The Attempt at a Solution

 

[Vorde]

Because an interference pattern (like the one you get in the two-slit experiment) only occurs when the objects interfering are waves, not particles.

 

[billVancouver]

Hi nukeman,

One of the key points of a two-slit experiment is that you can fire a single electron at a time at the slits, and if you don't detect which slit it goes through, you will still observe an interference pattern built up over time. This doesn't make sense if the electron is a classical particle going through one slit or the other; only by interpreting it as a wave could this be possible.

In reality, the 'wavelike' behavior here is that of the electron's wavefunction, the probability distribution of where it could be. But a lot of the amazing / confusing results of early QM come from the conflation of what an object 'is' with its wavefunction. Anyway, this point is probably too subtle for your test, so don't worry about it; see the first paragraph about behavior observed when firing single electrons at a time :)

Hope this helps,
Bill Mills

 

[Simon Bridge]

For the sake of (being pedantic) completeness - the two slit experiment for electrons does not demonstrate that electrons are waves - exactly. It demonstrates wave-like behavior for electrons (which were not normally expected to display wave-like behavior) and so provides evidence for the general applicability of quantum wave mechanics... which predicts this behavior yea even for lumps of matter.

The experiment does not tell us if the electron is a wave but that some of it's behavior is best modeled using the same math we normally use to describe waves. This is so close to he same thing, and so long-winded, that we don't normally bother with the distinction - but it's there, an important one, and creates a lot of confusion in students if they don't bear it in mind.

@irfan104 - you are a tad off topic: how did you get on?
If you are having this sort of trouble so close to an exam, then it is probably too late: you will find the method in your notes. You should already know it and have practiced it through the course.

 

[Nickie]

The two-slit experiment is a classic experiment that demonstrates the wave-like behavior of particles. In this experiment, a beam of electrons is passed through two parallel slits and observed on a screen behind the slits. According to classical physics, the electrons should form two distinct bands on the screen, corresponding to the two slits. However, this is not what is observed. Instead, an interference pattern is observed, similar to what is seen when light waves pass through two slits. This can only be explained by the electrons behaving like waves, as they interfere with each other to create the pattern.

This experiment provides strong evidence that electrons, despite being considered as particles, also exhibit wave-like behavior. This is known as wave-particle duality and is a fundamental concept in quantum mechanics. The electrons behave as waves, with a wavelength determined by their momentum, and can interfere with each other just like waves. This phenomenon cannot be explained by classical physics and is a key piece of evidence for the wave nature of electrons.

Additionally, the results of the two-slit experiment have been replicated with other particles, such as protons and even large molecules, further supporting the idea of wave-particle duality. This experiment has also been extended to demonstrate the wave-like behavior of other particles, such as photons, which are traditionally thought of as waves.

In conclusion, the two-slit experiment with electrons provides strong evidence for the wave-like behavior of particles, including electrons. This experiment has played a crucial role in shaping our understanding of quantum mechanics and the dual nature of particles.