Uniformly charged rod in an arc

In summary: If you define the resultant field to be along the x-axis, so that the arc is from (3/4)pi to (1), all of the y components will cancel.
  • #1
StephenDoty
265
0
If a rod with charge density lambda is bent into a 3/4 circle what is the E field at the center?


Well if the rod is 3/4 of a circle then neither the x or y components can cancel out, thus

E= k*lambda/ R (i) + k*lambda/R (j)

right?
 
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  • #2
You need to tell us how the circular arc is oriented. And I don't see how you got that. I got a different answer for magnitude.
 
  • #3
from pi/2 to 2pi

meaning the test particle would go up and to the right.

as I drew the lines of E I couldn't tell how any component could cancel, and if you spit it up neither the x or y component cancel out as the r's are different. If the rod was a half circle the y's would cancel out but if it is just a 1/4 circle there is an x- and y-components, thus for a 3/4 circle there would be x- y- components.

and if you add another 1/4 of a circle you would get a ring at which there is no E field at the center. and if you draw two dq lines from opposite sides of the 3/4 circle arc the resultant would be going up and to the right.

After that I just integrated x and y components from pi/2 to 2pi as my instructor indicated.
 
Last edited:
  • #4
StephenDoty said:
from pi/2 to 2pi

meaning the test particle would go up and to the right.

as I drew the lines of E I couldn't tell how any component could cancel, and if you spit it up neither the x or y component cancel out as the r's are different. If the rod was a half circle the y's would cancel out but if it is just a 1/4 circle there is an x- and y-components, thus for a 3/4 circle there would be x- y- components.

You can redefine your axes so that one set of components will cancel. For example, if you define the resultant field to be along the y-axis, so that the arc is from (3/4)pi to (1/4)pi, all of the x components will cancel.
 

Related to Uniformly charged rod in an arc

1. What is a uniformly charged rod in an arc?

A uniformly charged rod in an arc is a physical system in which a long, thin rod is bent into a circular shape and has a uniform distribution of electric charge along its length.

2. What is the electric field at a point on the axis of a uniformly charged rod in an arc?

The electric field at a point on the axis of a uniformly charged rod in an arc is given by the formula E = (kQx) / (x^2 + R^2)^3/2, where k is the Coulomb's constant, Q is the total charge on the rod, x is the distance from the center of the arc to the point, and R is the radius of the arc.

3. What is the electric potential at a point on the axis of a uniformly charged rod in an arc?

The electric potential at a point on the axis of a uniformly charged rod in an arc is given by the formula V = (kQ) / (x^2 + R^2)^1/2, where k is the Coulomb's constant, Q is the total charge on the rod, x is the distance from the center of the arc to the point, and R is the radius of the arc.

4. How does the electric field and potential change as you move along the axis of a uniformly charged rod in an arc?

As you move along the axis of a uniformly charged rod in an arc, the electric field and potential will decrease as the distance from the rod increases. This is because the electric field and potential are inversely proportional to the distance from the charge.

5. How is the electric field and potential affected if the uniformly charged rod in an arc is made of a different material?

The electric field and potential of a uniformly charged rod in an arc will be affected by the material it is made of. Different materials have different dielectric constants, which will affect the electric field and potential. In general, materials with higher dielectric constants will result in stronger electric fields and potentials.

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