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

In summary: However, this equation will still be a useful tool for understanding how an RC circuit works.In summary, the resistor in an RC circuit affects the electric field between the capacitor, and the charging process results in the current going to zero.
  • #1
kfreshn
5
0
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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  • #2
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?
 
  • #3
IR(t) + q(t)/C = V(t)?

edit: thanks for the welcome
 
  • #4
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.
 
  • #5
So will the resistor in the RC circuit affect the electric field between the capacitor? V=ED?

Ty for your help.
 
  • #6
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?
[tex]Ri(t) + \frac{1}{C}q(t) = V(t)[/tex]

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.
 

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

1. What is an RC circuit?

An RC circuit is a circuit that contains a resistor (R) and a capacitor (C) connected in series or parallel. The capacitor stores electrical charge, while the resistor controls the flow of current in the circuit.

2. How does a capacitor affect voltage drop in an RC circuit?

In an RC circuit, the capacitor acts as a voltage divider. As current flows through the circuit, the capacitor charges up and creates a voltage drop across it. This voltage drop is inversely proportional to the capacitor's capacitance and the rate of change of voltage across it.

3. What is the time constant of an RC circuit?

The time constant of an RC circuit is a measure of how quickly the capacitor charges or discharges. It is calculated by multiplying the resistance (R) and capacitance (C) of the circuit, and is measured in seconds.

4. How does the value of resistance affect voltage drop in an RC circuit?

The value of resistance (R) in an RC circuit affects the rate at which the capacitor charges and discharges. A higher resistance will result in a slower charging and discharging process, while a lower resistance will result in a faster process.

5. How can I calculate the voltage drop across a capacitor in an RC circuit?

The voltage drop across a capacitor in an RC circuit can be calculated using the formula V = V0(1-e-t/RC), where V0 is the initial voltage, t is the time, R is the resistance, and C is the capacitance. Alternatively, you can use a circuit simulator or measure the voltage drop with a voltmeter.

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