00:01
For part a of our question, it says to find the magnitude of the force per unit length that one wire exerts on the other from these two parallel wires that are carrying currents in the opposite direction.
00:11
They're separated by the distance d, which i convert from centimeters to meters.
00:15
I1 is the current in wire 1, and i2 is the current in wire 2.
00:19
So to calculate this, we just simply need to use our equation for force per unit length, which says that f over l, force per unit length is equal to mu not, the magnetic permeability of free space, times the current, in the two wires, so this is multiplied by i1 and then multiplied by i2, divided by two times pi times the distance that separates the two wires, d.
00:45
Mu not here is, again, is the magnetic permeability of free space.
00:49
It's equal to 4 pi times 10 to the minus 7.
00:51
You plug these values in and we find that this force per unit length is equal to 3 .5 times 10 to the minus 5 newtons per meter.
01:05
We can box this in as our solution for part a.
01:13
Part b says, is the force attractive or repulsive? so according to the right -hand rule, the magnetic field that's created by the first wire is directed into the paper or into the page at the position of the second wire.
01:29
Therefore, the second wire experiences a magnetic force that is directed away from the first wire...