18.2 | Resistors in Series 593 Quick Quiz R2 83 In Figure 18.5, the current is m

Question

18.2 | Resistors in Series 593 Quick Quiz R2 83 In Figure 18.5, the current is measured with the ammeter at the bottom of the rcuit. When the switch is opened, does the reading on the ammeter (a) increase, ) decrease, or (c) not change? 4 The circuit in Figure 18.5 consists of two resistors, a switch, an ammeter, and attery. When the switch is closed, power P is delivered to resistor Ri. When switch is opened, which of the following statements is true about the power P. A. Figure 18.5 (Quick Quizzes 18.3 and 18.4)

Explanation / Answer

(18.3)

Resultant resistance is greater in series combination of resistors as compared to those resistors in parallel.

When switch is open, the resistor are in series. The resultant resistance increases. As resistance increases, the current decreases, since they are inversely proportional. Hence, the reading on ammeter decreases.

Correct option is (b)

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(18.4)

Expression for power:

P = I2 R

Power is P, current is I and resistance is R.

When switch is open, resistors are in series. So, resultant resistance is increases. Hence, net current decreases. As I ( current) decreases, power ( P) delivered to the resitor R1 decreases when switch is open.

Po < P c

Correct option is (a)

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