Electric Potential at Radius R of Concentric Spheres

In summary, the conversation discusses the equation V=kQ/R and how it applies to finding the potential at different points between infinity and the outer side of the outer shell. The answer is B) kQ/R, and the reasoning behind this is that the potential at any point between infinity and the outer side is just V=KQ/R, and going through the outer shell to the inner side changes the potential by practically zero. The conversation also touches on the distance and total charge in the equation, and how to integrate the E field to find the potential. It is concluded that the potential is KQ/R since the Qs cancel out.
  • #1
lorx99
21
0

Homework Statement



upload_2018-10-4_21-12-24.png

Homework Equations


V=kQ/R

The Attempt at a Solution


The answer is B)kQ/R. It is because V= k(2Q)/R. I don't understand why Q=2Q in this case. Isn't the point on the inside of the outer shell, so the Q for the equation is just Q?
 

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  • #2
lorx99 said:

Homework Statement



View attachment 231679

Homework Equations


V=kQ/R

The Attempt at a Solution


The answer is B)kQ/R. It is because V= k(2Q)/R. I don't understand why Q=2Q in this case. Isn't the point on the inside of the outer shell, so the Q for the equation is just Q?
The potential at any point between infinity and the outer side of the outer shell is what?
And going thru the outer shell itself to the inner side of the outer shell changes that potential by how much?
 
  • #3
rude man said:
The potential at any point between infinity and the outer side of the outer shell is what?
And going thru the outer shell itself to the inner side of the outer shell changes that potential by how much?
Potential from any point between inifitiy and outer side is just V=KQ/R. Going thru the outshell to just inner side of outershell is practically zero? So, is that why it is just V=KQ/R?
 
  • #4
lorx99 said:
Potential from any point between inifitiy and outer side is just V=KQ/R. Going thru the outshell to just inner side of outershell is practically zero? So, is that why it is just V=KQ/R?
Edit: your answer is right but you reasoned wrong.
What is the distance in this case? What is the total charge?
 
Last edited:
  • #5
rude man said:
Edit: your answer is right but you reasoned wrong.
What is the distance in this case? What is the total charge?
I am confused. What distance you mean?
 
  • #6
lorx99 said:
I am confused. What distance you mean?
The distance d in the formula for potential kQ/d. Or, to find the potential by integrating the E field, what are the limits of integration?
 
  • #7
rude man said:
The distance d in the formula for potential kQ/d. Or, to find the potential by integrating the E field, what are the limits of integration?
I think i understand. First, integrate from infinity to 2R which is K2Q/(2R). Then integrate from outer to inner surface of the outer shell, it would be 0 because E=0 inside the shell since V integeates over the efield which is just zer0. So the potential is KQ/r since the Qs cancel.
 
  • #8
lorx99 said:
I think i understand. First, integrate from infinity to 2R which is K2Q/(2R). Then integrate from outer to inner surface of the outer shell, it would be 0 because E=0 inside the shell since V integeates over the efield which is just zer0. So the potential is KQ/r since the Qs cancel.
Straight A!
 

1. What is the formula for calculating the electric potential at radius R of concentric spheres?

The formula for calculating the electric potential at radius R of concentric spheres is V = kQ/R, where V is the electric potential, k is the Coulomb's constant, Q is the total charge of the sphere, and R is the distance from the center of the sphere.

2. How does the electric potential at radius R of concentric spheres differ from the electric potential of a single sphere?

The electric potential at radius R of concentric spheres is the sum of the electric potentials of each individual sphere, whereas the electric potential of a single sphere only takes into account the charge and distance from the center of that specific sphere.

3. Can the electric potential at radius R of concentric spheres be negative?

Yes, the electric potential at radius R of concentric spheres can be negative if the total charge of the spheres is negative. This indicates that the electric potential is decreasing as the distance from the center of the spheres increases.

4. How does the distance between the concentric spheres affect the electric potential at radius R?

The distance between the concentric spheres does not have a direct effect on the electric potential at radius R. However, the electric potential at radius R will depend on the distance from the center of the spheres, which in turn can be affected by the distance between the spheres.

5. What is the unit of measurement for electric potential at radius R of concentric spheres?

The unit of measurement for electric potential at radius R of concentric spheres is volts (V). This is the same unit used for electric potential in general.

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