Capacitor Question Homework: Finding the Potential Difference

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In summary, the conversation discusses a circuit problem involving a switch, a capacitor, and resistors. The solution involves finding the equivalent resistance, current, and potential difference. It is determined that with the switch closed for a long time, no current flows through the capacitor or the 10 Ohm resistor. The purpose of the 10 Ohm resistor is unclear.
  • #1
Snazzy
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Homework Statement


2mhwndg.jpg




Homework Equations


V = IR
CV = Q



The Attempt at a Solution


I found the equivalent resistance to be 68 Ohms, then I found the current, then I found that the current splits 4/5 of its total across the branch with the capacitor, but if I apply Kirchhoff's loop law, I just get that the capacitor has a potential difference of 0 V.
 
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  • #2
"The switch has been closed for a long time."

I don't know how this should be apparent an introductory level but...

With the switch closed for a while, everything is static, the currents are done changing because the capacitor has as much charged as it's going to get. So...

No current flows through the capacitor. It's, like, an open circuit.
 
  • #3
Oh...so then no current also flows through the 10 Ohm resistor?
 
  • #4
You've got it. well done
 
  • #5
Okay, so if the 2nd branch doesn't affect the circuit, the current is 100 / (60+40) = 1A, and so the voltage difference across the 40 Ohm resistor is equal to the voltage difference across the capacitor? :S
 
  • #6
Snazzy said:
Okay, so if the 2nd branch doesn't affect the circuit, the current is 100 / (60+40) = 1A, and so the voltage difference across the 40 Ohm resistor is equal to the voltage difference across the capacitor? :S

That's correct.
 
  • #7
What's the point of that 10 Ohm resistor then?
 
  • #8
I dunno. It would effect the charge rate when the switch is closed. Ask your prof.
 

What is a capacitor?

A capacitor is an electronic component that stores electrical energy in the form of an electric field. It is made up of two conductive plates separated by an insulating material, also known as a dielectric.

What is potential difference?

Potential difference, also known as voltage, is the difference in electric potential energy per unit charge between two points in an electric field. It is measured in volts (V).

How do you calculate potential difference in a capacitor?

The potential difference in a capacitor can be calculated by dividing the charge stored on one plate by the capacitance of the capacitor. It can also be calculated by multiplying the electric field strength by the distance between the plates.

What factors affect the potential difference in a capacitor?

The potential difference in a capacitor is affected by the amount of charge stored on the plates, the distance between the plates, and the type of dielectric material used. It is also affected by the voltage of the power source connected to the capacitor.

Why is it important to calculate potential difference in a capacitor?

Calculating potential difference in a capacitor is important because it allows us to understand the behavior of the capacitor in a circuit. It helps us determine the amount of energy stored in the capacitor and how it will react to different voltages. This information is crucial in designing and troubleshooting electronic circuits.

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