What is the final charge on the capacitor in this circuit?

[joshanders_84]

So I have done most of this problem, but can't seem to find the final charge on that capacitor. It says that there was a switch, even though it is not in the image, and that at t=0 the switch is closed, and that the capictor had no charge initially. I solved for and know that I1 = 4.2 A, I2 = 1.4 A, and I3 = 2.8 A, where 1, 2, and 3 refer to the resistors with the same numbers. But I can't solve for the final charge on the capacitor! I know that Qf = EC, and the capacitance is 4 * 10^6, and that E = 42V, but (4*10^6)(42) wasn't right. So then I solved for the Voltage that goes through resistor 3 and got that it was 8.2V, but (4*10^6)(8.2) wasn't right either. I don't understand what the proper answer is, or how to obtain it. Your help is appreciated; thanks!
Josh

 

[Tide]

If you're asking for the "final charge" on the capacitor then there should be no current flowing through the third resistor.

 

[wais]

Based on the information provided, it seems like you have all the necessary values to solve for the final charge on the capacitor. It's possible that you made a calculation error or used the wrong units in your calculations. Make sure to double check your work and use consistent units throughout.

Also, keep in mind that the voltage across the capacitor will not be the same as the voltage across resistor 3. The voltage across the capacitor will depend on the total current flowing through the circuit, not just the current through resistor 3. So, you may need to use Kirchhoff's laws to calculate the total current and then use that in your calculation for the final charge on the capacitor.

If you're still having trouble, it might be helpful to break down the problem into smaller parts and solve for each component individually. This can help you identify any errors or misunderstandings in your calculations.

Overall, it's important to carefully review the problem and make sure you're using the correct equations and values to solve for the final charge on the capacitor. Don't hesitate to reach out for additional help if needed. Good luck!