Dirac Delta Function: What It Does & How to Evaluate It

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Discussion Overview

The discussion revolves around the Dirac Delta Function, specifically its evaluation and properties in three dimensions. Participants explore its definition, application in physics, and the relationship between the three-dimensional and one-dimensional forms of the function.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant asks about the purpose and evaluation of the three-dimensional Dirac Delta Function, ##\delta^3(\vec{r})##, and its values across the real number line.
  • Another participant questions the effectiveness of online resources in explaining the concept.
  • A participant clarifies that the vector ##\vec{r}## represents a function of three variables: x, y, and z.
  • One response suggests that the Dirac Delta Function is typically introduced in Quantum Mechanics or Electromagnetism courses, referencing Griffiths' texts for a non-rigorous introduction.
  • A later reply explains that the three-dimensional Dirac Delta Function can be expressed as the product of three one-dimensional delta functions, indicating a relationship between the dimensions.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on the evaluation of the Dirac Delta Function or its properties, and multiple viewpoints regarding its explanation and application are present.

Contextual Notes

There are limitations in the discussion, such as the lack of detailed mathematical steps for evaluating the Dirac Delta Function and the dependence on specific definitions that may not be universally agreed upon.

Philosophaie
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What does the Dirac Delta Function do?

##\delta^3(\vec{r})##

How do you evaluate it?

What are its values from -inf to +inf?
 
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Did google yield no useful results?
 
It did not explain the vector r
 
The vector just means that it is a function of x, y, and z.

Beyond that, I would say that you should try a bit harder to learn about the delta function without just asking us to explain it. It is typically introduced in either a Quantum mechanics course or an Electromagnetism course. Griffiths text on both subjects gives a non rigorous intro to the delta function.
 
So are you familiar with the 1-dimensional Dirac delta function? If so, the 3-dimensional delta function is just the product of three 1-dimensional delta functions, one for each component of the vector ##\vec{r}##:

##\delta^3(\vec{r}) = \delta(r_x)\delta(r_y)\delta(r_z)##
 

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