# What is the formula of probability current density?

## What is the formula of probability current density?

again as long as V(x) is real. In three-dimensions, Eqs. (9.3), (9.4), and (9.5) can be generalized to ∇ · J + ∂ρ/∂t = 0, ρ(r,t) = Ψ*(r,t)Ψ (r,t), and J(r,t) = (ħ/2mi) {Ψ *(r,t) ∇Ψ (r,t)] − [∇Ψ *(r,t)]Ψ (r,t)}.

What is probability and probability current density?

Probability currents are analogous to mass currents in hydrodynamics and electric currents in electromagnetism. As in those fields, the probability current is related to the probability density function via a continuity equation. The probability current is invariant under gauge transformation.

### What is probability current density and continuity equation?

Continuity Equation ∂ t | Ψ | 2 + ∇ ⋅ J = 0. We can write this in a more suggestive form by denoting the probability density as ρ=|Ψ|2 ρ = | Ψ | 2 , then we have the equation ∂tρ+∇⋅J=0, ∂ t ρ + ∇ ⋅ J = 0 , which is called the continuity equation.

What is the unit of probability current density?

So, current density has units of A/m2 because it is an areal density. Probability density in a 3D position space has units of m−3.

#### What are probability and probability density in quantum mechanics?

In quantum mechanics, a probability amplitude is a complex number used for describing the behaviour of systems. The modulus squared of this quantity represents a probability density.

How do you find the probability density of a wave function?

The probability density (or probably distribution) is given by taking the square of the absolute value of the wave function. It gives us the likelihood of finding an electron (or some other system) at some given point in space.

## What does the wave function ψ represent?

Wave Functions. A wave function (Ψ) is a mathematical function that relates the location of an electron at a given point in space (identified by x, y, and z coordinates) to the amplitude of its wave, which corresponds to its energy. Thus each wave function is associated with a particular energy E.

What is probability density in quantum physics?

General Quantum Mechanics Probability Density. Probability density is the probability of finding a wave packet in a given region of phase space.

### What is probability density Schrodinger wave equation?

If we turn off h, we get Ψ = 0, which seems reasonable – classically, the probability density would be given by: ρ(x, t)CM = δ(x − x(t)), so that with probability 1, the particle is on its classical trajectory x(t).

What is probability density physics?

Probability density is the probability of finding a wave packet in a given region of phase space.

#### What is the probability current in probability density?

Specifically, if one describes the probability density as a heterogeneous fluid, then the probability current is the rate of flow of this fluid. This is analogous to mass currents in hydrodynamics and electric currents in electromagnetism. It is a real vector, like electric current density.

What is probability current in quantum mechanics?

In quantum mechanics, the probability current(sometimes called probability flux) is a mathematical quantity describing the flow of probability (i.e. probability per unit time per unit area). Intuitively, if one pictures the probability density as an inhomogeneous fluid, then the probability current is the rate of flow of this fluid.

## What is the probability current of a plane wave?

Plane wave. (that is, plane waves are stationary states) but the probability current is nonzero – the square of the absolute amplitude of the wave times the particle’s speed; illustrating that the particle may be in motion even if its spatial probability density has no explicit time dependence.

Is the probability current a real vector?

It is a real vector that changes with space and time. Probability currents are analogous to mass currents in hydrodynamics and electric currents in electromagnetism. As in those fields, the probability current is related to the probability density function via a continuity equation. The probability current is invariant under gauge transformation .