00:01
So this question basically asks, how do you detect that a magnetic field exists? and it does say in a region of space.
00:12
First, i want to look at figure 17 .16.
00:17
Figure 17 .16.
00:24
And it shows a source of voltage, which is like a battery, that goes through.
00:34
Springs, both the positive and the negative side, go through springs, creating a current, of course, that's going to flow through a rod down here.
00:53
So if we had such an apparatus, we would find that if, and in this case, the field is coming out of the paper, then we would see deflection in the rod because the magnetic force would create deflection.
01:29
So i'm going to write force of b on the wire or the rod.
01:40
Now, we know that if the rod is perpendicular as shown here to the magnetic field, then there will be a downward force.
01:58
But if we turn the rod 90 degrees into the plane of the paper so that it's in the direction of the magnetic field, then we should not see any force and therefore any extra deflection of the spring.
02:22
And so we should be able to turn this 90 degrees with our hands, like this way, just turn the apparatus and look for any deflection, any extra deflection of the apparatus as it slowly turns.
02:46
All right.
02:46
Secondly, i would like to look at figure, and i intended to be writing in black here, 17 .18, and moving down the page 17 .19 as well...