Problem 10-21 Source:
Problem elaborated by the author of the site.
From the circuit shown in Figure 10-21.1, determine:
a) The values of I and I1.
b) The power dissipated by the resistor 14 ohms.
Solution of the problem using Kirchhoff's law
click here!
Solution of the Problem 10-21
To calculate the current I , one must calculate the equivalent resistance of
the entire circuit.
Initially we will calculate the equivalent resistance between the points a-b .
Looking closely at the circuit, we can see
that the resistor of 5 Ωis in series with that of 15 Ω,
results an equivalent resistance of this branch, equal to 20 Ω. On the
other hand, in the branch formed by
resistors of 33 Ω and 47 Ω which are in series, results in
a resistance
equivalent, of this branch, of 80 Ω. And these two branches are in parallel resulting in a resistance
equivalent between points a-b of
To find the equivalent resistance value for the entire circuit, just calculate
the series of the three resistors.
Then:
Now, to calculate the value of I just apply Ohm's law , or:
And to calculate I1 , just apply a current divider to node a , or
To calculate the power that the 14 resistor dissipates, just check that
the
electric current flowing through it is I = 1.5 A . Then, applying the
equation eq. 7-02 , studied at
chapter 7 , we have:
