00:01
In a simple circuit in which you have a battery that you can adjust the voltage v and a resistor of resistance r, what do you expect to have happened to the current, if you could measure the current, is that we expect the current to obey oms law.
00:20
V equals the product of the current times the resistance.
00:26
This is known as oms law, and it really isn't.
00:31
A law in the sense that this is always true because of a physical reason.
00:39
It is a phenomenon.
00:41
So a lot of materials behave this way.
00:45
Anyway, we can check and see if the law holds by making the measurements.
00:51
Here we have some measurements in a little chart of the potential and the current that was measured.
01:00
And if we plot those on a graph, we expect them then to lie on a straight line.
01:08
This equation v equals ir is a direct proportion.
01:15
And in fact, it's such a direct proportion.
01:19
We can even add a point that we expect to be true, which is that we expect no current when the voltage is zero.
01:29
And just making a hand drawing, we can see that indeed the points do appear to lie fairly nicely on a straight line.
01:38
The slope of this line, current plotted in amps on the horizontal axis, the slope is expected then to be equal to the resistance.
01:53
So i did this by hand just so that we can go through a slope calculation...