Why do E and G both degrade by 1/r^2?

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In summary, the electric and gravitational fields "die off" at 1/r^2. This is due to the geometry of the situation and is not a general rule for all the fundamental forces.
  • #1
Ghost117
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Both the electric and gravitational fields 'die off' at 1/r^2 ... why?

Is this 1/r^2 value based on a geometric property (area of a sphere) alone? If so, then why don't all the fundamental forces degrade by this same value?

Thanks
 
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  • #2
The 1/r^2 is purely due to geometry - if you have any charge or mass distribution other than a sphere or point source, the 1/r^2 goes away and the field is more complicated.
 
  • #3
Ghost117 said:
If so, then why don't all the fundamental forces degrade by this same value?

can you name one that doesn't ?
 
  • #4
Then why doesn't the strong force also degrade by 1/r^2 ?
 
  • #5
Ghost117 said:
Then why doesn't the strong force also degrade by 1/r^2 ?

that's correct, the strong nuclear force and also the weak nuclear force degrade differently
Basically, it is all to do with the mediating particles and if they have mass or not
The strong nuclear force which has the mediator particle as a gluon is only strong at atomic distances.
as is the weak nuclear and its mediator particles the W and Z bosons

EM radiation is mediated by the photon and has no mass and as a result the range of an EM field is infinite

Im not a particle physicist ... I don't want to go any deeper than that :wink:

Dave
 
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  • #6
That helps, so it's not just geometry, or more specifically, the geometric reasoning only applies when the mediating particles are mass-less... Thanks.
 
  • #7
the 1/r^2 thing is basically the way something radiating from a point decreases in a three dimensional space. A line source decreases at 1/r and if we lived in four spatial dimensions instead of three, a point source would decrease as 1/r^3.
 
  • #8
cosmik debris said:
the 1/r^2 thing is basically the way something radiating from a point decreases in a three dimensional space. A line source decreases at 1/r and if we lived in four spatial dimensions instead of three, a point source would decrease as 1/r^3.

But that's not the complete answer (1/r^2 only applies to 2 of the 4 forces.) See Davenn's response above.
 

1. Why does the strength of E and G decrease with distance?

The decrease in strength of E and G is due to the inverse square law, which states that the strength of a force is inversely proportional to the square of the distance between the objects. This means that as the distance between two objects increases, the force between them decreases exponentially.

2. What causes E and G to degrade by 1/r^2?

This degradation is a result of the geometry of space. The inverse square law applies to any force that radiates outward from a point source in three-dimensional space, such as electric and gravitational fields. As the distance from the source increases, the energy is spread out over a larger area, leading to the decrease in strength by a factor of 1/r^2.

3. How does the inverse square law affect E and G?

The inverse square law has a significant impact on the behavior of E and G. It states that the force between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. This means that as the distance between two objects decreases, the force between them increases exponentially.

4. Is the 1/r^2 degradation of E and G consistent in all situations?

Yes, the 1/r^2 degradation of E and G is a fundamental law of physics and is consistent in all situations. It applies to any point source in three-dimensional space, regardless of the masses or charges of the objects involved.

5. Can the 1/r^2 degradation of E and G be observed in everyday life?

Yes, the inverse square law and the resulting degradation of E and G can be observed in many everyday situations. For example, the light from a distant street lamp appears dimmer than a closer lamp due to the decrease in light intensity with distance, which follows the inverse square law. Similarly, the gravitational force between the Earth and an object on its surface decreases as the object moves farther away from the Earth's center.

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