Are These Expressions for Probability Current Density Equivalent?

In summary, the conversation discusses finding the equivalent expressions for probability current density and the use of complex numbers and integration by parts in solving the problem. The solution is a pure math problem and the first equation can be obtained by substituting the real part of the second equation.
  • #1
qwijiboo
2
0
Hi folks!

Can someone tell me how to solve the following... I'd really appreciate it.

Homework Statement



Show that the below two expressions for probability current density are equivalent.

j(r,t) = h'/2im([tex]\Psi^{*}[/tex][tex]\Delta\Psi[/tex]- ([tex]\Delta\Psi^{*}[/tex])[tex]\Psi[/tex]]

j(r,t) = real part of [[tex]\Psi^{*}[/tex] (h'/im) [tex]\Delta\Psi[/tex]]


Homework Equations


h' is the reduced Plancks constant h/2pi


The Attempt at a Solution




 
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  • #2
You should really give us your thoughts (or at least a guess) on this. But if c is a complex number, what's the relation between Im(c) and Re(c/i)? And you may also want to think about integration by parts.
 
  • #3
I'm sorry... but I figured it out. Its a pure math problem. Sometimes my brain just ceases to work!

RP of the second equation is {j(r,t) + [j(r,t)]*}/2 substituting ,we get the first equation.

Thanks anyways for replying to my post.
 

1. What is probability current density?

Probability current density is a concept in quantum mechanics that describes the flow of probability through a given point in space. It is represented by the symbol J, and is related to the probability density and the wave function of a particle.

2. How is probability current density calculated?

Probability current density is calculated using the Schrödinger equation, which takes into account the wave function, potential energy, and mass of a particle. It is also related to the gradient of the probability density.

3. What is the significance of probability current density?

Probability current density is important in understanding the behavior of particles in quantum systems. It can be used to determine the rate of change of the probability density at a given point, and provides insight into the flow of probability in a system.

4. How does probability current density relate to other quantum mechanical concepts?

Probability current density is closely related to other important concepts in quantum mechanics, such as probability density, wave function, and quantum probability. It is also related to the concept of momentum, as it describes the flow of probability over time.

5. Can probability current density be measured?

Probability current density cannot be directly measured, as it is a mathematical concept. However, its effects can be observed through experiments and calculations, and can provide valuable information about the behavior of particles in quantum systems.

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