Dielectric inserted into a parallel plate capacitor

The charge remains constant, so increasing the capacitance means the voltage decreases.In summary, the potential between the plates of a capacitor (of thickness d) is initially V, but after inserting a dielectric of thickness t with relative permitivity Er, the new potential becomes V/d(d - t + t/Er). The electric field is not constant, but the charge remains constant, causing the voltage to decrease due to the changing capacitance.
  • #1
Vriska
138
2

Homework Statement


The capacitor (of thickness d) is disconnected from a potential source of V and a dielectric of thickness t is inserted and it has relative permitivity Er. Find the new potential between the plates

Homework Equations


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This is the answer : Vf = V/d(d - t + t/Er)

The Attempt at a Solution



I don't get why this is it looks like they assumed that the electric field would remain constant and just added the potential drops. We know electric field isn't constant so what give?
 
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  • #2
The charge is isolated and so is the only thing that remains constant.
The voltage changes as a result of the changing capacitance. C = Q / V.
 

Related to Dielectric inserted into a parallel plate capacitor

What is a dielectric inserted into a parallel plate capacitor?

A dielectric inserted into a parallel plate capacitor is a material that is placed between the two plates of the capacitor, and it is used to increase the capacitance of the capacitor. The dielectric material has a high dielectric constant, which means it can store more electric charge than air or vacuum.

What is the purpose of inserting a dielectric into a parallel plate capacitor?

The purpose of inserting a dielectric into a parallel plate capacitor is to increase the capacitance of the capacitor. This means that for a given voltage, the capacitor is able to store more electric charge, making it more efficient in storing electrical energy.

What are the different types of dielectric materials used in parallel plate capacitors?

The most commonly used dielectric materials in parallel plate capacitors are air, vacuum, paper, mica, ceramic, and plastic materials such as polyethylene and polystyrene. The choice of material depends on the specific application and the desired dielectric constant.

How does inserting a dielectric affect the electric field and potential difference in a parallel plate capacitor?

Inserting a dielectric into a parallel plate capacitor changes the electric field and potential difference between the plates. The electric field decreases as the dielectric constant increases, while the potential difference remains constant. This results in an increase in the capacitance of the capacitor.

What are the advantages of using a dielectric in a parallel plate capacitor?

The main advantage of using a dielectric in a parallel plate capacitor is that it allows for a larger capacitance without increasing the physical size of the capacitor. This makes it more compact and efficient in storing electrical energy. Additionally, dielectric materials can also provide insulation, making them useful in high voltage applications.

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