What are the units of A and δ in Dirac's delta function?

In summary, A has the same units as E, which is Joules. The delta function, represented as \delta, is dimensionless and has units of the reciprocal of the integration variable. This can be seen from the equation \int _{-\infty} ^{\infty} \delta (p-p_0) dp = 1, where p is any parameter.
  • #1
Gonzolo
Consider :

[tex] E = \int P(\tau) d\tau = \int A\delta(\tau) d\tau [/tex]

E is in Joules and [tex]P(\tau)[/tex] is in Watts, what are the units of A? What about [tex]\delta[/tex]?

I have a hunch, but need to have all doubts removed.
 
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  • #2
The delta function has the dimension of the reciprocal of the variable of integration. Thus delta(tau)d(tau) is non-dimensional. Therefore A has the same dimension as E, i.e. Joules.
 
  • #3
And you can see why the dirac delta has units of the reciprocal of the integration variable from

[tex] \int _{-\infty} ^{\infty} \delta (p-p_0) dp = 1 [/tex],
where p is any parameter.
 
  • #4
Thanks guys!
 

1. What is Dirac's delta function?

Dirac's delta function, also known as the Dirac delta distribution, is a mathematical function that is used to describe a point mass or impulse at a specific location. It is commonly denoted by the symbol δ(x) and has a value of zero everywhere except at the point where x = 0, where it has an infinite value. It is often used in physics and engineering to represent idealized point sources or to simplify mathematical calculations.

2. How is Dirac's delta function related to units of measurement?

Dirac's delta function is often used in physics and engineering to convert between different units of measurement. For example, if we want to convert from meters to centimeters, we can represent the conversion factor of 100 centimeters per meter as δ(x-100). This allows us to easily integrate over the function and obtain the desired conversion.

3. Can Dirac's delta function be used to represent physical quantities?

No, Dirac's delta function is not a physical quantity itself, but rather a mathematical tool to represent idealized point sources or to simplify calculations. However, it is often used in physics and engineering to model physical quantities, such as point charges or point masses.

4. How does the unit of Dirac's delta function cancel out in calculations?

When using Dirac's delta function in calculations, the unit of the function will cancel out with the unit of the physical quantity being represented. This is because the function is often multiplied by a physical quantity to convert between units, and the units will cancel out in the final result.

5. Can Dirac's delta function be used in all mathematical operations?

No, Dirac's delta function has certain properties that make it useful for integration and simplification of calculations, but it cannot be used in all mathematical operations. For example, it cannot be multiplied or divided by another function, and it cannot be raised to a power. It is important to understand its limitations when using it in mathematical calculations.

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