In the circuit shown in the figure (Figure 1) . the 6.0 ?resistor is consuming e
ID: 1323640 • Letter: I
Question
In the circuit shown in the figure (Figure 1) . the 6.0 ?resistor is consuming energy at a rate of 24.0J/s when the current through it flows as shown.
Part A
Find the current through the ammeter A.
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Part B
What are the polarity and emf of the battery E, assuming it has negligible internal resistance?
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In the circuit shown in the figure (Figure 1) . the 6.0 ?resistor is consuming energy at a rate of 24.0J/s when the current through it flows as shown.
Part A
Find the current through the ammeter A.
I = ASubmitMy AnswersGive Up
Part B
What are the polarity and emf of the battery E, assuming it has negligible internal resistance?
E = VSubmitMy AnswersGive Up
In the circuit shown in the figure (Figure 1) . the 6.0 ?resistor is consuming energy at a rate of 24.0J/s when the current through it flows as shown Part A Find the current through the ammeter A. I = A Part B What are the polarity and emf of the battery E, assuming it has negligible internal resistance? E = VExplanation / Answer
24 J/s is the same as 24 watts. If a 6 ohm resistor is dissipating 24 watts, then it must be passing 2 amps and have a voltage drop of 12 volts.
The 25 volt battery and the 3 ohm resistor is also in this series string and will therefore have the same current flow. We already determined there is 12 volts across the 6 ohm resistor, and we can determine there will be 6 volts across the 3 ohm resistor.
The voltage between the top of the 6 ohm resistor and the bottom of the 3 ohm resistor will be
25 - 12 - 6 = 7 volts.
The equivalent resistance in series with the ammeter is 30 ohms. Therefor the ammeter will read
I = E/R = 7/30 = 0.2333 amps.
If we have 2 amps coming out of the center branch, and 0.2333 amps are flowing through the ammeter, then 1.7666A must be flowing through the voltage source and two series resistors on the left.
17 + 13 = 30 ohms. To get 1.7666 A to flow through 30 ohms requires and EMF of
E = IR = 1.7666*30 = 53 volts.
We already have 7 volts, so we need 46 volts more. Note that the voltage needs to add, and the EMF source shown in the diagram is subtracting. So the require EMF of battery E is -46 volts.