And so if I plug that in the voltage at b then is going to just be the, voltage at

b is just the voltage at the battery. And multiplied by this factor, so that

tells you how much of the battery voltage appears across R2.

The remainder of that voltage must be dropped across R1.

So the 2 things to take away from this is that series resistance.

Is the sum of the two resistors in series or this applies to multiple resistors

series. And then the voltage divider equation,

which we wrote above. So, a few special cases.

Let's say that R1 and R2 are equal. So then, the voltage at this midpoint

here Would be half of the vol, voltage of the battery.

Or another case, let's say R2 is much bigger than R1, then the voltage at point

b is going to approach the voltage of the battery.

All of the voltage of the battery is going to be dropped across the large

resistor. So you see if I take, if I look at this

expression here and I say if R2 is really big, much bigger than R1, then the

denominator here is almost the same as R2, and so R2 over R2 is 1.

So the rule is when I have a voltage divider, the greater amount of the

voltage is dropped across the larger resistor.