Transcript The Parallel Plate Capacitor

By: Griffin Thomas
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A capacitor is an electrical device that stores energy. Most electrical
devices have some capacitance either intentional or accidental
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The energy is stored by maintaining a potential difference
between two conductors.
The energy is stored in the electric field between the conductors
Any electrical device that creates electrical fields creates some
capacitance
The geometry of the capacitor affects the amount of energy
stored. Capacitors are rated by capacitance, C, which is the ability
of a given capacitor to store charge.
A dielectric is a material that when used in a capacitor increases
the efficiency of the capacitor
A capacitor is unlike a power supply (which also maintains an
electrical potential between two points) in that it is limited by the
fact that it can store only a finite amount of charge.
Capacitance is the ratio of the magnitude of the charge in a capacitor
to the magnitude of the potential difference in the capacitor
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Capacitance is always a positive quantity
Capacitance is a measure of the ability of a device to store charge
and electrical potential energy.
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Units of capacitance:
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1 Farad is a huge amount of capacitance.
Typical capacitors have values on the order of 10-12 (picofarads)
to 10-6 (microfarads)
Capacitance depends upon the geometric arrangement of the
conductors (plates)
If one ignores the fringing field then the field
between the plates is uniform. The distance
between the plates is d.
• The field lines are parallel
• The field lines are perpendicular to each plate
 For an electric field between two parallel plates
then:
• Vb −VA = −Ed
 The minus sign indicates
that plate B is at a lower potential
than plate A,VB < VA.
 Parallel plate capacitors
are essential in physics
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The charge density for each plate is
E between conducting plates is
The potential between the plates is
Note that capacitance for a parallel plate
capacitor is proportional to area and inversely
proportional to d.
https://www.youtube.com/watch?v=CFzCDg9yp7Q
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After watching the video and learning more, Lets
solve a problem together. Remember ( C = Q/V )
1). Determine the amount of charge stored on either
plate of capacitor (4x10^-6F) when connected across a
12 volt battery.
 C = Capacitance
 Q = Charge
 V = Volts
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Answer: Q = (48x10^-6C)
Give yourselves a pat on the back
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Definition: Having the property of transmitting electric force without
conduction; insulating.
Dielectrics increase the maximum operating voltage of a capacitor.
(Capacitance)
Dielectrics may increase the mechanical strength of a capacitor.
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Example:
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After introduction of the dielectric material, the preexisting field
polarizes the dielectric.
Polarization of the dielectric establishes a field within the dielectric
that opposes the external field causing the capacitance to increase
thus strengthening the system. Invisible bonds man. Learn about ‘em.
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Now lets jump into a new segment of dielectrics. Lets find
the area of the conductive plates. This is the formula:
Tip: Absolute permeability (dielectric) (e) = 8.85x10^-12
1). If the plate separation for a capacitor is 2.0x10^-3 m,
determine the area of the plates if the capacitance is exactly
1 F.
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Answer: 2.3x10^8 m^2
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Parallel series are circuits that conduct
electricity from a power source. With capacitors
involved they can get trickier.
I will explain this in the schematics.
Does anybody know how to make this look simpler?
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Solution?
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By getting rid of all three capacitors you can make the
same circuit by creating a single capacitor with the total
amount of capacitance.
Now how do you calculate total capacitance with similar
and non-similar values like so:
Here is the first equation equation:
Note: this is only if there are 2 capacitors
 Now here is the equation if there are more than 3
capacitors in a series:
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Lets solve the total capacitance together.
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Hint: There are 3 capacitors.
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You did it guys! Hooray! You beat the capacitance
and dielectrics crash course! Bravo!