Dielectric slab in between plates of capacitor

In summary, the conversation discusses a method for calculating the equivalent capacitance of two capacitors in series. One person questions the assumption of treating two plates and a dielectric slab as one capacitor while another justifies it by adding a hypothetical conducting plate.
  • #1
karanbir
7
0
i'm reposting this question as nobody answered it previously. please answer it this time.

in given type of arrangement we normally take it equivalent to two capacitors(plate 1 and surface 2) and (surface 2 and plate 3) in series. My question is that a capacitor is formed with two plates of equal and opposite charge but the induced charge on dielectric slab(surface 2) is less than the charge on plates 1 and 3 which is clear by the formula q(ind)=q(1-1/k), then how can we assume plate 1 and surface 2 as one capacitor?
 

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  • #2
making demands on people for answers is not the wisest way to engender help

definately doesn't encourage me to help you :(

Dave
 
  • #3
Here is one way to justify this method:
Place a hypothetical conducting plate (with infinitesimal thinness) on the other face of the dielectric and you have two capacitors in series now! Since the plate doesn't change the electric field E , the voltage difference between the two REAL plates remains the same. So does charge Q on each plane which depends on the normal component of E. Thus the ratio Q/V=C is also remains the same.
 

1. What is a dielectric slab in a capacitor?

A dielectric slab is a material with a high dielectric constant that is placed between the plates of a capacitor. It is used to increase the capacitance of the capacitor and store more electrical charge.

2. How does a dielectric slab affect the capacitance of a capacitor?

A dielectric slab increases the capacitance of a capacitor by reducing the electric field between the plates. This allows for more charge to be stored on the plates and increases the overall capacitance.

3. What materials are commonly used as dielectric slabs in capacitors?

The most commonly used materials as dielectric slabs in capacitors are plastic, ceramic, and paper. These materials have high dielectric constants and are able to withstand high electric fields.

4. What are the advantages of using a dielectric slab in a capacitor?

Using a dielectric slab in a capacitor allows for a higher capacitance, which means the capacitor can store more charge. It also helps to reduce the electric field and prevent breakdown of the capacitor. Additionally, dielectric materials are often cheaper and more readily available than metal plates, making them a cost-effective choice for increasing capacitance.

5. Are there any disadvantages of using a dielectric slab in a capacitor?

One potential disadvantage of using a dielectric slab is that it can decrease the maximum voltage that the capacitor can withstand. This is because the high dielectric constant of the material allows for more charge to be stored, which can lead to a higher voltage across the capacitor. However, this can be mitigated by selecting a dielectric material with a high breakdown voltage. Dielectric materials can also introduce losses and reduce the overall efficiency of the capacitor.

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