Problem 13-5 Source:
Problem elaborated by the author of the site.
For the circuit shown in the Figure 13-05.1, compute by the laws of the nodes of Kirchhoff and law of Ohm the current I,
i2 and the voltage V1, knowing that i1 = 1A.
Solution of the Problem 13-5 -
Kirchhoff Method
The only information given by the problem is that i1 = 1A.
Calculating the parallel between the resistors of 5 and 20 ohms results in one of 4 ohms . Thus,
between the point a and the point y we have a total resistance of 8 + 4 = 12 ohms.
Now we can determine the voltage at the point a, or:
With this information we can calculate the current that flows through of the
4 ohms resistor, or:
With this information we can calculate the value of I, because:
To calculate i2, we can use a resistive current divider:
It is necessary to calculate the parallel between the resistors of 30
and 60 ohms , which results in a equivalent resistance of Req = 20 ohms. Thus, we can calculate the value of
V1.
Note that, we use the value of Vxa = 4 Req = 4 x 20 = 80 volts.
