How Can a Capacitor be Charged to the Voltage of the Battery in an RC Circuit?

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SUMMARY

The discussion focuses on the charging behavior of a capacitor in an RC circuit connected to a 10V battery. It clarifies that according to Kirchhoff's Law, the sum of the voltage drops across the resistor and capacitor must equal the battery voltage. Initially, the resistor causes a voltage drop, but as the capacitor charges, the current decreases to zero, resulting in the full battery voltage appearing across the capacitor. Understanding the differential equation relating current and charge is essential for analyzing this circuit's behavior.

PREREQUISITES
  • Understanding of Kirchhoff's Voltage Law
  • Familiarity with resistor-capacitor (RC) circuits
  • Knowledge of differential equations
  • Basic concepts of electric fields and voltage
NEXT STEPS
  • Study the differential equation for RC circuits: Ri(t) + (1/C)q(t) = V(t)
  • Learn about the charging and discharging processes of capacitors in RC circuits
  • Explore the implications of self-inductance in RLC circuits
  • Investigate the relationship between electric field (E) and voltage (V) in capacitors
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Students studying electrical engineering, educators teaching circuit theory, and hobbyists interested in understanding RC circuit behavior.

kfreshn
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Resistor Capacitance Circuits.Say there is a resistor before a capacitor connected in a wired circuit; and there is a battery as the emf source (10V for example).

Chapter2960.gif


How can the capacitor be charged to approx. the voltage of the battery if the voltage drop across the resistor = the voltage of the battery (V=IR and Kirschoff's Law states the voltage drop across the resistor should equal the Voltage of the battery)?

I guess I'm having trouble understanding how a resistor can reduce voltage of the circuit to 0, and yet current is still able to flow after it leaves the resistor --- albeit at a slower rate?.

I thought of Voltage = 0, there would be no more current movement. Need explanation on this.

And how can the Capacitor be charged to the voltage of the battery. If voltage drop across resistor is 10V, how can the capacitor be charged to 10V?

ugh.

Thanks for all the help in advance.

I'll Forever grateful for anyone who can help me asap :)
 
Last edited:
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kfreshn said:
Resistor Capacitance Circuits.


Say there is a resistor before a capacitor connected in a wired circuit; and there is a battery as the emf source (10V for example).

Chapter2960.gif


How can the capacitor be charged to approx. the voltage of the battery if the voltage drop across the resistor = the voltage of the battery (V=IR and Kirschoff's Law states the voltage drop across the resistor should equal the Voltage of the battery)?

I guess I'm having trouble understanding how a resistor can reduce voltage of the circuit to 0, and yet current is still able to flow after it leaves the resistor --- albeit at a slower rate?.

I thought of Voltage = 0, there would be no more current movement. Need explanation on this.

And how can the Capacitor be charged to the voltage of the battery. If voltage drop across resistor is 10V, how can the capacitor be charged to 10V?

ugh.

Thanks for all the help in advance.

I'll Forever grateful for anyone who can help me asap :)

Welcome to the PF.

(I moved your thread to here in the Homework Help section of the forums, where schoolwork questions like this should be posted.)

Are you familiar with the differential equation that relates v(t) and i(t) for a capacitor? That's really the key to understanding how this circuit behaves. Can you show us that equation?
 
IR(t) + q(t)/C = V(t)?

edit: thanks for the welcome
 
kfreshn said:
harged to approx. the voltage of the battery if the voltage drop across the resistor = the voltage of the battery (V=IR and Kirschoff's Law states the voltage drop across the resistor should equal the Voltage of the battery)?

No, Kirchoff's law says the sum of the voltages around a closed loop should be zero, so the resistor voltage drop PLUS the capacitor voltage drop must add up to the battery voltage. At the end of the charging process, the current goes to zero, which means there is no voltage drop across the resistor, and all of the battery voltage has developed across the capacitor.

Also: what berkeman said.
 
So will the resistor in the RC circuit affect the electric field between the capacitor? V=ED?

Ty for your help.
 
kfreshn said:
IR(t) + q(t)/C = V(t)?

edit: thanks for the welcome

To describe the charging of an RC circuit, you'll need to solve this ODE. First, you need to get it in terms of one variable. How can you write i in terms of q?
Ri(t) + \frac{1}{C}q(t) = V(t)

Note that the solution to this equation is wrong. To accurately describe the circuit, you'll need to take self-inductance into account, which will give you an RLC circuit, which you should get to soon.
 

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