Derivation of mechanism of charging capacitor

In summary, the conversation discusses deriving the mechanism of a charging capacitor in a circuit with a battery, capacitor, resistor, and switch in series. The process involves differentiating the charge equation, using Kirchhoff's law, and integrating from time 0 to t and potential difference 0 to V. The conversation also addresses the question of why the potential difference is integrated from 0 to V, which is due to the fact that when the switch is closed, the amount of charge and potential difference increases until it reaches the applied potential difference.
  • #1
thereddevils
438
0
I am trying to derive the mechanism of a charging capacitor , V=Vo(1-e^(-t/CR))

sorry , i couldn't upload the diagram here so i will briefly describe it , its a circuit with a battery (Vo) , connected to a capacitor (Vc) , and resistor (VR) and also a switch , all in series .

i started with

Q=CVc , then differentiate w r t to time t ,

[tex]\frac{dQ}{dt}=\frac{d}{dt}(CV_c)=C\frac{dV_c}{dt}[/tex]

using kirchhoff law , [tex]V_o=V_R+V_c[/tex] (Refer to the diagram)

[tex]=IR+V_c[/tex]

[tex]=CR\frac{dV_c}{dt}+V_c[/tex]

[tex]\frac{1}{RC}dt=\frac{dV_c}{V_o-V_c}[/tex]

Integrate from time , 0 to t ,

and also integrate from potential difference , 0 to V ,

Here is my question , why integrate the pd from 0 to V ??

I understand that the capacitor is initially at a constant potential difference , then when the switch is closed , the amount of charge increases , followed by the pd between the capacitors .

is my thought process even correct ? Thanks in advance .
 
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  • #2
When the switch is closed , the amount of charge increases. PD across the capacitor also increases until its PD is equal to the applied PD.
 
  • #3
rl.bhat said:
When the switch is closed , the amount of charge increases. PD across the capacitor also increases until its PD is equal to the applied PD.

thank you , so when the capacitor is not charged , there is no pd , and when its charged , the pd becomes v (the applied pd) , so integrate within this range . Thanks !
 

Related to Derivation of mechanism of charging capacitor

1. How does a capacitor charge?

A capacitor charges by accumulating and storing electrical energy in the form of an electric field between two conductive plates separated by an insulating material.

2. What is the mechanism behind charging a capacitor?

The mechanism behind charging a capacitor involves the flow of electrons from a power source to one of the plates, creating a buildup of negative charges. This accumulation of charges creates an electric field that pulls in positive charges from the other plate, resulting in a charged capacitor.

3. What factors affect the speed of charging a capacitor?

The speed of charging a capacitor is affected by the voltage of the power source, the capacitance of the capacitor, and the resistance in the circuit. A higher voltage and capacitance or lower resistance will result in a faster charging time.

4. What is the equation for calculating the time it takes to charge a capacitor?

The equation for calculating the charging time of a capacitor is t = RC, where t represents time in seconds, R is the resistance in ohms, and C is the capacitance in farads.

5. Can a capacitor be overcharged?

Yes, a capacitor can be overcharged if the voltage exceeds its maximum rating. This can cause damage to the capacitor or result in a discharge of a high amount of energy, potentially causing harm to the surrounding circuit or individuals.

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