What happens to capacitance and voltage when a battery is disconnected?

In summary, the conversation discusses the behavior of voltage and capacitance when a battery is connected and disconnected from a capacitor. The importance of a dielectric in storing more charge on the plates and preventing them from touching is also mentioned. The conversation also mentions the constant electric field between the plates and how it is affected by the distance. A video demonstration by Prof Lewin is suggested for further understanding.
  • #1
FahimP
14
0
hello i need some explanation on this .
I know that when a battery is connected it provides constant voltage across the capacitors. But the happens when the battery is disconnected. What happens to the voltage, the capicitance, and what is the importance of dielectric.

I have read the book the researched online but i can't seem to find an explanation on what happens when the battery is connected and when it is disconnected. PLEASE HELP
 
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  • #2
When you charge up a capacitor and then disconnect the battery the charge is stuck on the plates . So if i increase the distance between the plates the voltage will go up. V=Ed
Because the electric field is constant between the plates . And the capacitance is only a function of geometry of the plates . And the dielectric allows more charge to be stored on the plates, and also so the plates don't touch each other.
 
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  • #3
In a parallel plate capacitor setup , If the distance is not to large the E field remains constant . I have a question for you, how do you find the electric field between the plates and the answer does not even have distance in it.
 
  • #4
Suppose the plates where infinite, do you still think that the E field will fall off, or do you think it would be constant between the plates.
 
  • #5

watch this video , Prof lewin explains capacitors and does a demo that shows the voltage will increase when you separate the plates. The E field is constant between the plates .
Start at about the 22min mark.
 
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  • #6
No problem , I've been wrong many times, And its a very strange concept .
 

What is a capacitance battery?

A capacitance battery is a type of battery that uses capacitors instead of traditional chemical reactions to store and release energy. It is also known as a supercapacitor or ultracapacitor.

How does a capacitance battery work?

A capacitance battery works by storing electrical energy in an electric field between two conductive plates separated by a dielectric material. When a voltage is applied, electrons are stored on one plate and pulled away from the other, creating a potential difference that can be used to power devices.

What are the advantages of a capacitance battery?

Capacitance batteries have several advantages over traditional batteries, including a longer lifespan, faster charging times, and the ability to store and release energy more quickly. They are also more environmentally friendly as they do not contain toxic chemicals.

What are the limitations of a capacitance battery?

One of the main limitations of a capacitance battery is its lower energy density compared to traditional batteries. This means that it can hold less energy per unit of volume or weight. Capacitance batteries also have a higher self-discharge rate, meaning they lose energy over time even when not in use.

What are some practical applications of capacitance batteries?

Capacitance batteries are commonly used as backup power sources for devices that require quick bursts of energy, such as cameras and flashlights. They are also used in hybrid vehicles and renewable energy systems to capture and store excess energy. Research is also being conducted to use capacitance batteries in larger-scale applications such as powering entire buildings.

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