1. Two 1.5 V cells are connected in series to a bulb with a resistance of 6 . If

Question

1. Two 1.5 V cells are connected in series to a bulb with a resistance of 6 . If the current through the circuit is 0.47 A, what is the internal resistance of each cell (assume the cells are identical and the wires have negligible resistance).

2. Suppose you have a 520 , a 640 , and a 890 resistor.

a. What is the minimum resistance you can obtain by combining these?

b. What is the maximum resistance you can obtain by combining these?

3. An RC circuit consists only of a resistor of 6.2 k and a capacitor of 4.0 F. If the capacitor starts with voltage V0 at t = 0, how long does it take the capacitor to discharge to 1% of its initial voltage?

Explanation / Answer

There are multiple questions here. . i am allowed to answer only 1 at a time. I will answer question 1 for you.Please ask other as different question.

Let internal resistance of each cell be r.
Then total resistance in cicuit = r + r + 6 = 2r + 6 ohm

V net = 1.5+1.5 = 3.0 V since 2 cell are connected in series

Now use:
Rnet = V/I
2r+6 = 3/0.47
2r+6 = 6.38
r= 0.19 ohm
Answer: 0.19 ohm

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