What is the meaning of ##d\Omega## in solid angle integration?

In summary, the conversation discusses how to perform two integrals involving unit vectors. The first integral is ##\int d\Omega n_{i}n_{j}## and the second integral is ##\int d\Omega n_{i}n_{j}n_{k}n_{l}##. The context is unclear and it is mentioned that the result should be proportional to a symmetrized product of Kronecker deltas. The participants also discuss the meaning of ##d\Omega##, which is described as a constant of the integration.
  • #1
PreposterousUniverse
22
2
Anyone have any idea how to perform the following two integrals?

##\int d\Omega n_{i}n_{j}## and ##\int d\Omega n_{i}n_{j}n_{k}n_{l}##

where the n is a unit vector.
 
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  • #2
Not if you don't provide some more context. The way it looks now (to me) it's nonsense (##n_in_j = \delta_{ij}## ? )
 
  • #3
BvU said:
Not if you don't provide some more context. The way it looks now (to me) it's nonsense (##n_in_j = \delta_{ij}## ? )
Actually, I think it should be proportional to some symmetrized product of kronecker deltas. But how can one show that?
 
  • #4
PreposterousUniverse said:
But how can one show that?
First you have to show what you mean. Isn't a unit vector a constant of the integration ?

Describe ##\;d\Omega##
 

Related to What is the meaning of ##d\Omega## in solid angle integration?

What is solid angle?

Solid angle is a measure of the amount of space an object takes up in three-dimensional space. It is defined as the angle formed by three intersecting planes that converge at a point. It is measured in steradians (sr).

What is the difference between solid angle and regular angle?

Regular angle is a measure of the amount of rotation between two lines, while solid angle is a measure of the amount of space an object takes up in three-dimensional space. Regular angle is measured in degrees or radians, while solid angle is measured in steradians (sr).

What is the purpose of using ##d\Omega## in solid angle integration?

##d\Omega## is used in solid angle integration to represent an infinitesimal element of solid angle. It is similar to using ##dx## in regular integration to represent an infinitesimal element of length. It allows for the integration of functions over a solid angle.

How is solid angle calculated?

Solid angle is calculated by dividing the area of a spherical cap by the square of the radius of the sphere. It can also be calculated by integrating a function over a solid angle using ##d\Omega##.

What are some real-world applications of solid angle?

Solid angle is commonly used in physics and engineering to calculate the amount of radiation or light emitted or received by a surface. It is also used in astronomy to measure the size of celestial objects and in computer graphics to simulate lighting and shading effects.

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