What determines an amplitude of a wave particle?

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Discussion Overview

The discussion revolves around the factors that determine the amplitude of a wave associated with a wave particle, particularly in the context of quantum mechanics. Participants explore the relationship between amplitude, wave functions, and probability densities, while referencing Schrödinger's equation and its solutions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Homework-related

Main Points Raised

  • One participant states that, according to Bohr's model, the frequency of a photon is determined by the energy difference between electron levels, raising the question of what determines the amplitude of the wave created by a single photon or electron.
  • Another participant explains that the amplitude of the wave function is related to the probability density of finding the particle at various locations, defined mathematically as ##P(x) = |\Psi|^2##.
  • A participant questions how to find the probability density without knowing the amplitude of the wave function, suggesting a dependency between the two.
  • In response, another participant clarifies that one must first solve Schrödinger's equation to find the wave function before determining the probability density.
  • A later reply expresses confusion about the process of solving Schrödinger's equation, asking for clarification on how to express the wave function and calculate amplitude based on defined energy and mass.
  • Another participant notes that Schrödinger's equation is a partial differential equation and mentions that finding exact solutions can be challenging, recommending studying simpler problems first.
  • One participant suggests that many students encounter Schrödinger's equation in introductory modern physics courses, highlighting common starting points like the "particle in a box" problem.

Areas of Agreement / Disagreement

Participants express varying levels of understanding regarding the relationship between amplitude and probability density, with some confusion about the process of solving Schrödinger's equation. There is no consensus on how to approach the calculation of amplitude.

Contextual Notes

Participants reference specific cases and examples related to Schrödinger's equation, indicating that the discussion is limited to certain scenarios in quantum mechanics. The complexity of solving the equation and the dependency on initial conditions and parameters are acknowledged.

Goodver
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According to Bohr's model, photon is emitted when electron "falls" to the lower level with energy equal to the difference between energies on these levels. This determines the frequency of the photon.

What determines an amplitude of a wave created by a single photon, or electron?
 
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In general, the amplitude of the wave function is related to the probability of finding the particle at various locations. More specifically the probability density is ##P(x) = |\Psi|^2 = \Psi^*\Psi## where ##\Psi^*## is the complex conjugate of ##\Psi##.
 
Yes, but then how can I find the probability density without knowing an amplitude of the wave function?

I mean, probability density and amplitude depends on each other, so if one side is unknown (amplitude in this case), then the other side also can not be determined
 
Goodver said:
Yes, but then how can I find the probability density without knowing an amplitude of the wave function?

You don't. First you find the wave function by solving Schrödinger's equation for the situation that you are interested in, then you use the wave function to find the probability density.
 
deleted
 
Sorry, I am still a bit confused.

by this:

jtbell said:
You don't. First you find the wave function by solving Schrödinger's equation for the situation that you are interested in.

You mean I should express ψ(x) from the time independent Schrödinger equation (attached)

substituting values for E, m, h etc (assume I want to calculate amplitude, for defined energy, mass)

?

Then how would I do that? I will always stay with the second derivative of the function and the function itself

Would appreciate if you can give some links on solving Schrödinger equation for this kind of cases
 

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Schrödinger's equation is a partial differential equation

Most of the time, it isn't easy (or just impossible) to find an exact solution, but there are about 5 or so instructive problems that are solved exactly in any Quantum mechanics textbook (e.g. Hydrogen atom, harmonic oscillator, etc...).

If you're interested in learning to solve it, I recommend you brush up on your calculus first, then study some quantum mechanics.
 
Many students get their first taste of solving Schrödinger's equation in an "introductory modern physics" course using a textbook such as the ones by Beiser, Tipler, etc.

Almost everyone starts with the "particle in a box" a.k.a. "infinite square well." A Google search should turn up a lot of web pages and university lecture notes.

The version of the SE that you showed is the one for the hydrogen atom. Don't tackle that one until you've done a couple of simpler examples first.
 

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