Dielectric slab in some space between a capacitor

In summary, when a dielectric slab is placed between two plates of a capacitor, it is equivalent to having two capacitors in series - one plate of the capacitor and the surface of the dielectric, and the other plate of the capacitor and the surface of the dielectric. This is an approximation because the charges on the surface of the dielectric are induced by the electric field of the capacitor plates, and they are not equal to the charges on the plates. However, since the electric field in the dielectric is usually much smaller, the induced charge is negligible and the dielectric can be treated as a single plate with a charge equal to the one on the plates and equal and opposite to the other plate.
  • #1
karanbir
7
0
when we place a dielectric slab between two plates of a capacitor(size small as compared to space between plates), we take it equivalent to 2 capacitors in series- one plate of capacitor and surface of dielectric and other plate of capacitor and surface of dielectric. My question is that a capacitor is formed with two plates having equal and opposite charge but the induced charge on surface of dielectric is less than charge on plates(q(induced)=q(1-1/k)), then how can we consider one plate of capacitor and surface of dielectric as a single capacitor?
 
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  • #2
A:It's an approximation. The electric field inside the dielectric is not uniform, and the charges on the surface of the dielectric are induced by the field of the capacitor plates. As you said, these charges are not equal to the charges on the plates.However, the electric field in the dielectric is usually much smaller than the one between the plates, so the induced charge is negligible compared to the one on the plates. This means that the dielectric behaves almost like a perfect conductor, so we can treat it as a single plate with a charge equal to the one on the plates and equal and opposite to the other plate.
 

What is a dielectric slab?

A dielectric slab is a material that can be inserted between the plates of a capacitor, which helps to increase the capacitance of the capacitor. It is an insulating material that can store energy in an electric field.

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

When a dielectric slab is inserted between the plates of a capacitor, it increases the capacitance of the capacitor by a factor of the dielectric constant of the material. This is because the presence of the dielectric slab reduces the electric field between the plates, allowing for more charge to be stored on the plates.

Can any material be used as a dielectric slab?

No, not all materials can be used as a dielectric slab. The material must have a high dielectric constant, which is a measure of how well it can store energy in an electric field. Examples of common dielectric materials include ceramic, glass, and certain types of plastics.

What is the purpose of using a dielectric slab in a capacitor?

The main purpose of using a dielectric slab in a capacitor is to increase its capacitance. This allows for the capacitor to store more charge and have a larger energy storage capacity. Dielectric slabs are often used in practical applications of capacitors, such as in electronic devices and power systems.

What are the potential drawbacks of using a dielectric slab in a capacitor?

One potential drawback of using a dielectric slab in a capacitor is that it can decrease the breakdown voltage of the capacitor. This means that the capacitor may not be able to withstand as high of a voltage before breaking down. Additionally, some dielectric materials may introduce losses and decrease the efficiency of the capacitor.

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