In the circuit shown in Fig. 25.3, avariable resistor R isconnected across the t
ID: 1757954 • Letter: I
Question
In the circuit shown in Fig. 25.3, avariable resistor R isconnected across the terminals of a battery, and an ideal ammeterand
ideal voltmeter are also connected. Inthe figure, ?? is theinternal emf of the battery, and r is itsinternal resistance. All the
connecting cables have no appreciableresistance. The ammeter reads 3.10 A when the voltmeter reads 5.08V, and the
voltmeter reads 15.0 V when theammeter reads 0.00 V.
5) In Fig. 25.3, the internal emf ofthe battery is closest to: 5)
A) 8.18 V B) 15.0 V C) 9.92 V D) 5.08 V E) 20.1V
Explanation / Answer
V=IR Apparently the power source is emitting 15V so therefore 15-5.08 =9.92 Volts dropped across the internalresistor the current is 3.10 A R=V/I so internal R = 9.92/3.10 = 3.2 Ohms which is closest to D)5.08