Chapter 23, Problem 75A

To determine

The unknown current in the circuit.

Answer to Problem 75A

The unknown current in the circuit is $I_3=11.3\text{ mA}$

Explanation of Solution

Given:

A circuit consisting of two parallel branch of resistors, connected in series with another resistor across a battery. The current $I_1=13\text{ mA}$ and $I_2=1.7\text{ mA}$

Formula used:

The sum of the current flowing through the individual parallel branches equals the total current in the circuit.

Calculation:

Consider the given circuit.

  

In the given circuit,

  $I_1=I_2+I_3$.......(1)

Substituting the given current values in the equation (1), current in the second branch, $I_3$ can be calculated as,

  $\begin{array}{l}13=1.7+I_3\\ I_3=11.3\text{ mA}\end{array}$

Conclusion:

The current in the required parallel branch of the circuit is 11.3 mA.