Amplitude of a particle

1. Jun 8, 2010

Simon43254

If a photon can be graphically demonstrated as a wave with amplitude x, what does the amplitude correspond to on a particle? Is it, it's displacement from its mean position at a given time?

2. Jun 8, 2010

Staff: Mentor

In quantum mechanics, the amplitude (at some location) of the wave that represents a particle corresponds to the probability of finding the particle at or near that location. More specifically,

$$P(x) = \Psi^*(x) \Psi(x)$$

where $\Psi$ is the wave function, which is generally complex, and P is the probability density.

3. Jun 8, 2010

Simon43254

Ok, on the quantum side that makes sense. So what about the classical?

4. Jun 8, 2010

Studiot

You need to know that the 'wave function' is not truly oscillatory like for example y=sin(x).

The wave function JT refers to is the solution of Schrodinger's 'wave' equation, which is not really a wave equation at all it is called that because it is similar to the true wave equation which has an oscillatory solution y=sin(x).

5. Jun 8, 2010

Academic

Classically, the amplitude of an EM wave is the magnitude of the E-field (by convention).

6. Jun 8, 2010

LostConjugate

Classical Mechanics is designed to work with only a large number of particles. It does not apply to a small number of particles or a single particle.

When developing classical physics we worked with objects like apples, large metal objects, people, etc. All things which are a large collection of particles. Even in QM the expectation values (which describes classical results) do not give accurate information about a small number of particles.

7. Jun 8, 2010

Staff: Mentor

Classical physics doesn't contain the notion of "photons." In classical physics, light is purely a electromagnetic wave phenomenon. Nor does it contain the notion of particles having wave-like behavior.

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