00:01
So we don't have the length given in the problem, but we do know the direction of the length.
00:10
So we can write the length vector to be, let's call it l vector to be equal to l times i -cap, where l is the length and we don't know it yet.
00:24
And probably we don't need it because we want to find the force per unit length.
00:29
Now let's use equation 27 .3.
00:35
So we have fb equal to cross product of length and magnetic field.
00:48
Now this is equal to i times l.
00:59
So we use this vector, this expression over here.
01:07
And b vector, the magnetic field vector is given to be 0 .0.
01:11
0 .4 tesla i cap minus 0 .36 tesla j cap plus 0 .5t tesla k cap.
01:24
Now if you plug this over here, you get, since we want force per unit length, let me just take this magnitude of l over here.
01:36
So now we have force per unit length and this is equal to i times i cap times vector...