Suppose in the figurethat I1 = I2 = 20 Aand that the separation between the wire
ID: 1678739 • Letter: S
Question
Suppose in the figurethat I1 = I2 = 20 Aand that the separation between the wires is 0.012 m. By applying an external magnetic field(created by a source other than the wires) it is possible to cancelthe mutual repulsion of the wires. This external field must pointalong the vertical direction. (a) Does the external field point up or down? updown Explain. (b) What is the magnitude of the external field? T *** I do not yet fully understand the concept of magnetic fieldsenough to grasp this problem. If anyone can clarify this problem,and recalls an equation for external magnetic field magnitude, thatwould be very helpful!!
Explanation / Answer
a)DOWN The B field at wire 2 created by wire 1, and the B field atwire 1 created by wire 2, both point up. The external B field must cancel this, so it pointsdown.
b)
The magnitude of the external B field is equal to the B fieldat wire 2 due to wire 1. It has magnitude: B = k I / r
= 2 x10-7 * 20 / 0.012
= 3.33 *10-4 T