When switch S in the figure below is open, the voltmeter V of the battery reads

Question

When switch S in the figure below is open, the voltmeter V of the battery reads 3.84 V. When the switch is closed, the voltmeter reading drops to 3.74 V, and the ammeter A reads 1.10 A. Assume that the two meters are ideal, so they don't affect the circuit.

Find the emf of the battery.

  V

Find the internal resistance of the battery.

  ?

Find the circuit resistance R.

  ?

When switch S in the figure below is open, the voltmeter V of the battery reads 3.84 V. When the switch is closed, the voltmeter reading drops to 3.74 V, and the ammeter A reads 1.10 A. Assume that the two meters are ideal, so they don't affect the circuit. Find the emf of the battery. V Find the internal resistance of the battery. ? Find the circuit resistance R.

Explanation / Answer

when switch is open no current flows hence the voltmeter reading is the battery emf

V(emf)= 3.84 V

when the switch is closed the reading drops to 3.74 V

and the ammeter reading is

1.1 A

now the voltage across the voltmeter

3.74= 3.84-(1.1)*r

1.1*r=0.1

therefore

r= 1/11 =0.0909 ohm

the same amount of voltage is drop across R

therefore

1.1*R=3.74 V

R=3.74/11 = 0.34 ohm

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