4) A battery with unknown emf (ɛ) and internal resistance (r) is connected to a circuit that involves an ideal voltmeter, a switch, and two resistors R1 -10, R2 =10 Q, as shown below. When the switch is connected to a, the voltmeter reads 7V. When the switch is connected to b, the voltmeter reads 10 V. Calculate the value of the internal resistance r.

4) A battery with unknown emf (ɛ) and internal resistance (r) is connected to a circuit that involves an ideal voltmeter, a switch, and two resistors R1 -10, R2 =10 Q, as shown below. When the switch is connected to a, the voltmeter reads 7V. When the switch is connected to b, the voltmeter reads 10 V. Calculate the value of the internal resistance r.

College Physics

10th Edition

ISBN:9781285737027

Author:Raymond A. Serway, Chris Vuille

Publisher:Raymond A. Serway, Chris Vuille

Chapter18: Direct-Current Circuits

Section: Chapter Questions

Problem 51AP: When two unknown resistors are connected in series with a battery, the battery delivers 225 W and...

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