When switch S in the figure (Figure 1) is open, the voltmeter V of the battery r

Question

When switch S in the figure (Figure 1) is open, the voltmeter V of the battery reads 3.15V . When the switch is closed, the voltmeter reading drops to 2.95V , and the ammeter A reads 1.65A . Assume that the two meters are ideal, so they don't affect the circuit.

1. Find the emf

2. fFind the internal resistance of the battery.

3.Find the circuit resistance R.

When switch S in the figure (Figure 1) is open, the voltmeter V of the battery reads 3.15V . When the switch is closed, the voltmeter reading drops to 2.95V , and the ammeter A reads 1.65A . Assume that the two meters are ideal, so they don't affect the circuit. Find the emf Find the internal resistance of the battery. Find the circuit resistance R.

Explanation / Answer

1. when switch is open, current=0

therefore voltmeter reading = emf = 3.15 V

2. s is closed

i = 1.65 A

V= E-i*r

2.95= 3.15-1.65r

r= (3.15-2.95)/1.65 =0.1212 ohms

3. current =E/R+r

1.65= 3.15/R+r

r+R = 1.91

R= 1.7878 ohms

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