Why is there force on a dielectric inserted into a capacitor

In summary, when a dielectric slab is partially inserted into a capacitor where voltage is held constant, there is a force pulling the dielectric further into the capacitor. This is because, in this scenario, the charge on the plates increases due to the presence of the dielectric material, which causes an increase in potential energy inside the capacitor. This increase in potential energy results in a force that pulls the dielectric material in. However, in the case where the capacitor is disconnected from the voltage source, there is no change in charge or potential energy, so there is no force pulling the dielectric in.
  • #1
BearShark
15
0
Hey, we have learned in class that if you partialy insert a dielectric slab into a capacitor where voltage is held constant, there is a force pulling the dielectric farther into the capacitor. This gets me consfued. I know the more dielectric material there is in the capacitor, the capacitence would increase. Since this capacitor is connected to a voltage source, and voltage is held constant, then the charge on the plates would have to increase. However, this would mean the potential energy inside of the capacitor would increase. Wouldn't that mean I would have to apply force to push the dielectric in? How come there's a force pushing it in?
 
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  • #2
There is two different cases:
1. Push dielectric material on a capacitor C with initial charge Q, disconnected to voltage source.
2. Push dielectric material on a capacitor C connected to a constant V voltage source.
Please, think about these cases.
 

FAQ: Why is there force on a dielectric inserted into a capacitor

What is a dielectric?

A dielectric is an insulating material that can be inserted between the plates of a capacitor. It is typically made of a non-conductive material such as rubber, glass, or plastic.

Why is a dielectric used in a capacitor?

A dielectric is used in a capacitor to increase its capacitance, or its ability to store electric charge. This is because the dielectric material can hold more electric charge than air or vacuum, which are the materials typically found between the plates of a capacitor.

What is the effect of a dielectric on the electric field in a capacitor?

When a dielectric is inserted into a capacitor, it reduces the strength of the electric field between the plates. This is due to the polarizability of the dielectric material, which allows it to align with the electric field and reduce its strength.

How does a dielectric affect the voltage of a capacitor?

The voltage of a capacitor remains the same when a dielectric is inserted, as the charge on the plates remains constant. However, the electric field strength is reduced, which means the voltage per unit distance (i.e. the capacitance) increases.

What is the role of a dielectric in preventing breakdown of a capacitor?

A dielectric helps to prevent the breakdown of a capacitor by increasing its capacitance and reducing the electric field strength. This means that the capacitor can store more charge without reaching its breakdown point, which is important for maintaining its functionality and preventing damage.

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