Delta Dirac: $\phi=-\pi+\epsilon$

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In summary, the conversation discusses the Dirac delta function and its behavior when the argument is not zero. The specific problem at hand involves finding the value of T in an equation involving the Dirac delta and a constant. The range of the angular coordinate, phi, is between -pi and pi, and it is mentioned that phi cannot be equal to pi in this range. The conversation also mentions the possibility of integrating over a specific range to include the relevant behavior of the Dirac delta function.
  • #1
alejandrito29
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if [tex]\phi[/tex] is a angular coordinate , between ([tex]-\pi,\pi[/tex])

¿how much is [tex]\delta(\phi-\pi)[/tex] with [tex]\phi=-\pi+\epsilon[/tex]?
 
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  • #2
The Dirac delta function yield zero unless it's argument is zero, in which case it yields 1 (this is an oversimplification, but it should do for the present discussion). In your case, the argument of the delta function is [tex]-2*\pi + \epsilon[/tex], so it should be zero. Did you mean to type, [tex]\phi=\pi + \epsilon[/tex]? In that case, the argument of the delta function would be just [tex]\epsilon[/tex], and then you need to get a bit more specific about how you are defining the delta function. Have you looked at this thread? https://www.physicsforums.com/showthread.php?t=73447
 
  • #3
SpectraCat said:
The Dirac delta function yield zero unless it's argument is zero, in which case it yields 1 (this is an oversimplification, but it should do for the present discussion). In your case, the argument of the delta function is [tex]-2*\pi + \epsilon[/tex], so it should be zero. Did you mean to type, [tex]\phi=\pi + \epsilon[/tex]? In that case, the argument of the delta function would be just [tex]\epsilon[/tex], and then you need to get a bit more specific about how you are defining the delta function. Have you looked at this thread? https://www.physicsforums.com/showthread.php?t=73447

then the dirac delta evaluated in (-2pi+epsilon) is 0 or infinite?
 
  • #4
specifically, i need to find T, in the follows equation:

[tex]\delta(\phi-\pi)+k=T\delta(\phi-\pi)[/tex]
where [tex]\phi[/tex] is between ([tex]-\pi,\pi[/tex])
 
  • #5
With that specific range the delta distribution is zero; phi can't become equal to pi. So you get the equation 0 + k = T*0.
 
  • #6
haushofer said:
With that specific range the delta distribution is zero; phi can't become equal to pi. So you get the equation 0 + k = T*0.

but, if i do:

[tex]\int^{\pi-\epsilon}_{-\pi+\epsilon}\delta(\phi-\pi)d\phi+\int^{\pi-\epsilon}_{-\pi+\epsilon} k=T\int^{\pi-\epsilon}_{-\pi+\epsilon}\delta(\phi-\pi)[/tex]

is correct??

pd: [tex]\phi[/tex] can be equal to [tex]\pi[/tex]...[tex]\phi[/tex] is between [tex](-\pi,\pi)[/tex]
 
Last edited:
  • #7
You want to integrate from pi-epsilon to pi+epsilon. That will include the relevant range of the dirac delta.
 

Related to Delta Dirac: $\phi=-\pi+\epsilon$

What is Delta Dirac?

Delta Dirac, or Dirac delta function, is a mathematical function used in fields such as physics and engineering to model the behavior of point-like particles or impulses. It is defined as zero everywhere except at the origin, where it is infinite, with total area under the curve equal to one.

How is Delta Dirac used in science?

Delta Dirac is used in various scientific disciplines for its ability to model point-like behaviors and impulses. In physics, it is used to describe the behavior of particles at a specific point in space and time. In engineering, it is used to model impulses or forces acting on a system. It is also used in signal processing, probability theory, and quantum mechanics.

What does the equation $\phi=-\pi+\epsilon$ mean in relation to Delta Dirac?

This equation is a specific form of the Dirac delta function, where $\epsilon$ represents a small positive number. It is used to model a narrow, high-amplitude spike at the point $\phi = -\pi$. The value of $\epsilon$ determines the width of the spike, with smaller values resulting in narrower spikes.

How does Delta Dirac relate to other mathematical functions?

Delta Dirac is a generalized function, meaning it cannot be defined using a single mathematical equation. It is often represented as a limit of a sequence of functions, such as a Gaussian function, as the width of the spike approaches zero. It is also closely related to the Kronecker delta function, which is discrete rather than continuous.

What are some real-world applications of Delta Dirac?

Delta Dirac has various real-world applications, such as in signal processing to model impulses or sudden changes in a system. It is also used in quantum mechanics to describe the behavior of particles at a specific point in space and time. In electrical engineering, it is used to model electrical pulses. It is also used in probability theory to model point events.

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