00:01
So we're given the circuit in figure 25 .30, except that the 5 -oam resistor is now replaced with an unknown resistor of resistance r.
00:19
And i've done a little bit of relabeling of the circuit, and i've put all the numbers that we're given here on the right -hand side.
00:27
So the mf is 16 volts, r1 is 1 .6 oms.
00:34
This is the unknown resistor.
00:36
R2 is 1 .4 oms.
00:39
E2 is 8 volts.
00:42
And the resistor that was 9 volts here, i just call it rbc, and again, maintain its value.
00:52
And we're also told a new feature, another new feature of this problem, that there's an ideal volt meter that's connected across bc, and it reads 1 .9 volts, rather.
01:09
And so i've just written here that vbc is 1 .9 volts.
01:13
And we're asked to find in part a the current in the circuit.
01:20
So finding the current in the circuit, we can use this equation right away, that vbc is equal to irbc right and from here we can find that the current is vbc over rbc and we're given both of these these quantities so we have 1 .9 volts divided by nine oms which is equal to 0 .0 which is equal to 0.
02:09
0 .21 amperes.
02:15
Now we're going to move on to part b of the problem.
02:21
In part b, we're asked to find the resistance r, that unknown resistance...