Electrostatic Potential Energy-related.

In summary, the equation E=(1/4πε0)(Q/r^2) can be used to calculate the energy stored in an electrostatic field between two radii, R and 2R. This can be done by integrating the energy density, given by (1/2)ε0|E|^2, over the specified volume. It is important to note that this concept of energy stored in an electrostatic field can be found in most textbooks on the subject.
  • #1
Tarabas
4
0

Homework Statement


E=(1/4πε0)(Q/r^2) for R<r<2R

Homework Equations


U= integral (2R,R) ( (ε0 E^2)/2*4πr^2 dr

The Attempt at a Solution


I have no idea where the U-formula comes from. Any help would be appreciated.
I added some pictures so that it could be easier to understand.
12.jpg
123.jpg
 
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  • #2
Hello Tarabas,

You might want to look through your textbook in the parts that talk about the energy stored in an electrostatic field. By that I mean the total energy it takes to create a given electrostatic field in the first place.

To point you in the right direction, the energy density (energy per unit volume) of an electrostatic field is

[tex] \frac{dU}{dV} = \frac{1}{2} \varepsilon_0 |E|^2 [/tex]

where [itex] dU [/itex] is the differential potential energy (the potential energy of the space enclosed within the differential volume), [itex] dV [/itex] here refers to the differential volume (where '[itex] V[/itex]' here stands for volume, not to be confused with potential or voltage) and [itex] E [/itex] is the magnitude of the electric field at that point in space. Really though, you should check your textbook because it's likely there are at least a few pages dedicated to this idea.

Now do you see how the answer you posted in the image is integrating the energy density over the specified volume? :wink: [Edit: which gives you the energy stored in that region of space between [itex] R [/itex] and [itex] 2R [/itex]]
 
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  • #3
collinsmark said:
Hello Tarabas,

You might want to look through your textbook in the parts that talk about the energy stored in an electrostatic field. By that I mean the total energy it takes to create a given electrostatic field in the first place.

To point you in the right direction, the energy density (energy per unit volume) of an electrostatic field is

[tex] \frac{dU}{dV} = \frac{1}{2} \varepsilon_0 |E|^2 [/tex]

where [itex] dU [/itex] is the differential potential energy (the potential energy of the space enclosed within the differential volume), [itex] dV [/itex] here refers to the differential volume (where '[itex] V[/itex]' here stands for volume, not to be confused with potential or voltage) and [itex] E [/itex] is the magnitude of the electric field at that point in space. Really though, you should check your textbook because it's likely there are at least a few pages dedicated to this idea.

Now do you see how the answer you posted in the image is integrating the energy density over the specified volume? :wink: [Edit: which gives you the energy stored in that region of space between [itex] R [/itex] and [itex] 2R [/itex]]

Thanks a lot. I actually checked my textbook and it was nowhere. :D
 

FAQ: Electrostatic Potential Energy-related.

What is electrostatic potential energy?

Electrostatic potential energy is the potential energy stored in an object due to its electrostatic charge. It is the energy required to bring two charged objects from infinity to a certain distance apart.

How is electrostatic potential energy calculated?

The electrostatic potential energy is calculated using the formula U = kQ1Q2/r, where k is the Coulomb's constant, Q1 and Q2 are the charges of the two objects, and r is the distance between them.

What is the relationship between electrostatic potential energy and distance?

The electrostatic potential energy is directly proportional to the distance between two charged objects. As the distance increases, the electrostatic potential energy decreases and vice versa.

How does the sign of the charges affect electrostatic potential energy?

The sign of the charges determines the direction of the electrostatic force and thus affects the electrostatic potential energy. Objects with opposite charges have negative electrostatic potential energy, while objects with the same charge have positive electrostatic potential energy.

What are some real-life applications of electrostatic potential energy?

Electrostatic potential energy has numerous applications, such as in generators, capacitors, and electrostatic precipitators. It is also essential in understanding the behavior of lightning and the formation of thunderclouds.

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