Find resistance of resistor in RC circuit

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SUMMARY

The discussion focuses on determining the resistance of resistor R7 in an RC circuit to maximize power when the switch is activated. The voltage across the capacitor, Vc, is initially set at 200V. Participants emphasize the application of Thevenin's theorem to find the equivalent voltage E3 before closing the switch, while also considering the impact of the current Is on the circuit's behavior. The steady-state condition of the capacitor is highlighted, indicating that it behaves like an open circuit during this analysis.

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  • Thevenin's theorem
  • Understanding of RC circuits
  • Basic circuit analysis techniques
  • Knowledge of steady-state conditions in capacitors
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  • Learn about steady-state behavior of capacitors in RC circuits
  • Explore power calculations in resistive components
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AndrejN96
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Homework Statement


Find the resistance of resistor R7 when the switch is turned on so that the power of that resistor is maximum in the circuit.

The voltage of the capacitor before the switch is turned on is Vc=200V.

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Homework Equations


Thevenin's theorem

The Attempt at a Solution


I believe I should be using Thevenin's theorem but I have no idea how to put it. Help would be appreciated.
 
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It looks like you should be first trying to determine the value of E3. Do this before the switch is closed.

Pay close attention to the role of ##I_s##: it renders the effects of several other components to be nil.

At steady state the capacitor "looks like" an open circuit, so you need to find E3 such that the voltage across the place where C connects is 200 V. The current ##I_s## plays an important role here.
 
gneill said:
It looks like you should be first trying to determine the value of E3. Do this before the switch is closed.

Pay close attention to the role of ##I_s##: it renders the effects of several other components to be nil.

At steady state the capacitor "looks like" an open circuit, so you need to find E3 such that the voltage across the place where C connects is 200 V. The current ##I_s## plays an important role here.
So is Is going to flow through R3 and Vc is going to be equal to E3-Is*R3, and I find E3 from there?
 
AndrejN96 said:
So is Is going to flow through R3 and Vc is going to be equal to E3-Is*R3, and I find E3 from there?
Looks like a good deduction:)
 
gneill said:
Looks like a good deduction:)
Appreciate it, a lot! :)
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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