Chapter 23.2, Problem 31SSC

To determine

To describe: the occurrence of the brightness of the two bulbs.

Explanation of Solution

Introduction:

If the resistor is added to the circuit at the point $C$ , the equivalent resistance of the branch will increase. But the total resistance of the circuit will decrease since the bulbs are connected in parallel.

Since current is inversely proportional to the resistance so the total current $I$ will increase and as a result, the current $I_2$ will also increase.

The bulbs 2 and 3 are connected in series. In a series circuit, the same current flows through each bulb. That is, the same current flows through each bulb.

The brightness of a light bulb is proportional to the power dissipation that is, $P=I^{2}R$ .

Since the bulbs are identical, the power depends only on the current $I$ . Thus, as $I_2$ increases, the brightness of the two bulbs also increases,

Conclusion:

Hence, the brightness of the bulbs will increase.