# Two infinite current sheets

1. Oct 16, 2009

### deerhunt713

1. The problem statement, all variables and given/known data

Two infinite sheets of current flow parallel to the y-z plane. The left-hand sheet, which intersects the x-axis at x = 0, consists of an infinite array of wires parallel to the z-axis with a density n = 910 wires/m and acurrent per wire of IL = 0.14 A in the +zdirection. The right-hand sheet, which intersects the x-axis at x = a = 12 cm, is identical to the left-hand sheet,except that it has a current per wire of IR = 0.14 A in the -z direction.

(a) Calculate the y-components of the net magnetic field in the following places: x1 = -15 cm, x2 =6 cm, and x3 = 24 cm. (The x- and z-components of the B-field are zero.)

B(x1)y = T *

B(x2)y = T

B(x3)y = T

image
https://online-s.physics.uiuc.edu/cgi/courses/shell/common/showme.pl?courses/phys212/fall09/homework/08/03/0805.gif [Broken]
2. Relevant equations

B=unI

3. The attempt at a solution

i have x1 and x3 are equal to 0,
i have tried (u0)nI and calculating B, then using the 2 B's and use superposition, but i cant get the right answer, and dont even know if im on the right track

Last edited by a moderator: May 4, 2017
2. Oct 17, 2009

### deerhunt713

i figured it out. its .00016009556
but how do i use this to figure out this question

(c) Return to the configuration of part (a).Suppose you want to have the region 0 < x < a able to confine electrons (e = 1.60 x 10-19C, m = 9.11 x 10-31 kg) that have been accelerated from rest through a 61 V electrostatic potential. If the electrons starting at x=a/2 are moving in the +x direction are to be stacked in circular orbits parallel to the x-z plane with centers on the plane x = a/2, what is the minimum current per wire required if IL and IR are equal in magnitude but opposite in direction?

IL = A

HELP: This builds on the previous homework set and associated lecture notes and text material. First, find an algebraic expressionfor the radius R of an electron's circular orbit in a spatially uniform B-field.
HELP: What's the radius of the largest circular orbit that can be fitted into the space between the current sheets? (Neglect the thickness of the current sheets themselves.) Combine this value with your (algebraic result) from part (a),and the radius of the largest possible orbit to solve for the requested value of the current.