00:01
In this question, we have two wires separated by 8 centimeters.
00:05
They carry currents that are equal in magnitude, but they are opposite in direction.
00:11
They can be shown in this diagram as perpendicular to the plane of the paper, so one is coming out and one is going in.
00:17
We know that we have a point p between them.
00:21
The magnitude of the magnetic field at this point p is 0 .01 tesla's, and it's in a negative y direction.
00:28
We also know it's two centimetres away from wire 1.
00:33
So what we need to use is the biosavir law, which is the magnitude of the magnetic field due to a long straight wire is equal to mu -0, which is a constant i over 2 pi r, where r is the distance from the point.
00:53
What we can also say is we're told that the magnitude of the, the direction of the field at the point p is in a negative wide.
01:00
Direction.
01:02
Because both of these wires have the same current, we know that the current in wire one must also create a magnetic field, which is at a negative y direction at this point, because they're both the same magnitude.
01:18
So in order for the net field at point p to be in negative y, as it's closer to wire one, the field created around y1 at that point must be also equal to negative y...