TABLE OF CONTENTS
CAPACITANCE OF A CAPACITOR
Introduction
A parallel plate capacitor’s performance is much improved when a dielectric is present since it increases capacitance, lowers the electric field,expanding the amount of energy that can be stored,avoiding dielectric failure,and facilitates electronic device stability and shrinking.
Because of these characteristics, dielectrics are essential to the design and use of capacitors in modern technology.
Increase in Capacitance
Increasing the Capacitance: The Benefit of Dielectric
A parallel plate capacitor’s performance is much improved when a dielectric is present since it increases the capacitor’s capacitance.
d – Separation between the plates
t – Thickness of the dielectric slab
Efree – Uniform electric field( between the plates)
Eind – Electric Field due to polarisation (inside the dielectric)
Enet – Net electric field(inside the dielectric)
C0 – Capacitance with vacuum between plates
C – Capacitance with dielectric between plates
σ – Charge per area
σind – Actuated (induced) charge per area
DIELECTRICS
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Dielectric forestalls(prevents) the two plates contacting each other.(keeps them separated)
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Dielectric builds the capacitance of the capacitor
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Dielectric builds the maximum potential difference between the plates before the capacitor begins to lead(conduct).
CAPACITANCE OF THE CAPACITOR (Vacuum between the plates)
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d - separation between the plates
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A - Area of the plate
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Ɛ0 -Permittivity of free space
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Permittivity is the resistance to an electric field.
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Dielectrics truly do have higher permittivity (offer high resistance to the field)
The capacitor can store more charge for the same voltage because the dielectric material lowers the electric field between the plates for a given charge. The material’s dielectric constant (k), which measures how much the capacitance increases in comparison to a vacuum (or air) between the plates, is used to quantify this.
Reduction in Electric Field
How Dielectrics Weaken Electric Fields
When a dielectric is introduced, the electric field between the plates weakens.The explanation is that when an electric field is present, the dielectric material becomes polarized, producing an opposing electric field that partially cancels out the original field. The net electric field between the plates is lowered as a result.
FREE ELECTRIC FIELD (BETWEEN THE PLATES)
INDUCED ELECTRIC FIELD
NET ELECTRIC FIELD
Energy Storage
Maximizing Capacitor Energy with Dielectrics
The energy stored in the capacitor increases due to the presence of the dielectric.
The reason is that as the capacitance increases, the energy stored E= 1/2C V*2 also increases for a given voltage. Alternatively, if the charge is fixed, the energy stored decreases because the voltage across the capacitor decreases.
The significance is that this makes capacitors with dielectrics more efficient for energy storage applications.
Prevention of Dielectric Breakdown
Dielectric Breakdown: A Shield for Capacitors
Dielectrics increase the maximum voltage that can be applied across the capacitor before breakdown occurs.
The reason is that the dielectric materials have higher breakdown strengths compared to air or vacuum. This allows the capacitor to operate at higher voltages without arcing or short-circuiting.
The significance is that,this is crucial for high-voltage applications, such as in power transmission systems or electronic circuits.
Polarization of the Dielectric
How Dielectrics Polarize to Enhance Capacitance
The dielectric material becomes polarized in the presence of an electric field.
The reason is that the electric field causes the alignment of dipoles within the dielectric (in polar materials) or the creation of induced dipoles (in non-polar materials). This polarization reduces the effective electric field between the plates.
The significance is that polarization is the fundamental mechanism by which dielectrics increase capacitance and reduce the electric field.
ELECTRIC FIELD
POTENTIAL DIFFERENCE BETWEEN THE PLATES
CAPACITANCE WITH DIELECTRIC
Practical Applications
Dielectrics in Action: Real-World Applications
Capacitors can be reduced in size without sacrificing capacitance by adopting dielectrics with high dielectric constants. Given the restricted space of modern devices, this is crucial.
By filling the gap between the plates, dielectrics give the capacitor mechanical stability and guard against deformation or physical harm.
Various dielectric materials can be used to adjust the capacitance for certain uses, including energy storage systems, filters, or circuit tuning.
Types of Dielectrics
Exploring Dielectric Materials: Types and Uses
Fixed Capacitors: Use solid dielectrics like ceramic, mica, or plastic.
Variable Capacitors: Use air or adjustable dielectrics for tuning purposes.
Electrolytic Capacitors: Use a liquid or gel electrolyte as the dielectric, allowing for very high capacitance values.
Conclusion
The introduction of a dielectric material between the plates of a parallel plate capacitor profoundly enhances its performance and versatility. By increasing capacitance, reducing the electric field, and enabling greater energy storage, dielectrics play a pivotal role in the functionality of capacitors.
Their ability to prevent dielectric breakdown and provide mechanical stability further solidifies their importance in both theoretical and practical applications. From miniaturized electronics to high-voltage systems, dielectrics are the unsung heroes that make modern technology possible.
In essence, dielectrics are not just passive fillers; they are active enablers that unlock the full potential of capacitors, making them indispensable in our increasingly electrified world.
LINKS TO
Energy stored in a capacitor
Capacitor ,its working and capacitance of a capacitor
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