1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Expectation Value

  1. Jun 28, 2008 #1
    We all know the concept of expectation value,it is the average of all possible outcomes of an experiment. Mathematically average of x is written as (Σnkxk / Σnk ). Quantum-mechanically nk is represented by probability density(P), where P = ∫Ψ*Ψ d3r,
    then <r> = ∫ r P(r) d3r -----------(1)
    or <r> = ∫ Ψ*(r) r Ψ(r) d3r--------(2) (normalisation condition)
    but when we consider expectation value of Energy operator (= ih∂/∂t) the two equations ,to me, not give the same results. Can anybody solve what’s that dilemma and where I am wrong
  2. jcsd
  3. Jun 28, 2008 #2
    The expectation of an operator H is defined as <[itex]\Psi[/itex]|H|[itex]\Psi[/itex]>. The form (1) above holds only under special circumstances.

    Note: H = ih∂/∂t is the energy operator only when expressed in the position representation.

Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Expectation Value
  1. Expectation value (Replies: 5)

  2. Expectation Values (Replies: 1)

  3. Expectation value (Replies: 2)