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5C10.u2 - Variable Parallel Plate Capacitor

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​5C10.u2 - Variable Parallel Plate Capacitor

Preview
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Title5C10.u2 - Variable Parallel Plate Capacitor
Objective

To demonstrate that you can vary the capacitor strength based on the position of plate overlap.​

StatusAvailable
Assembly Instructions

Connect a multimeter to the variable capacitor apparatus using banana cables.  Set the multimeter to measure capacitance and use a camera to display the meter output to the audience.  Start with the two sets of plates not overlapping at all.  This should give you a reading of zero capacitance.  Then rotate the lever arm until the two sets of plates are entirely overlapping.  This should give you a reading of approx. 1.2nF. 

The radius of each plate is 6 inches.  There are 6 top plate surfaces.  Each of the top plates are a 180 degree of a circle and have areas of 58 sq inches.  The Range of Capacitance we have been able to achieve with this design is C = 0 to 1.2nF.

Setup Time3
Operation Time5
Preview Time5
Operation Instructions

Make sure the camera output is visible to the audience and that the multimeter is currently running.  With the two sets of plates not overlapping at all, you should get a reading of zero capacitance.  As you slowly rotate the lever arm, the capacitance reading should increase.  Once the two sets of plates are completely overlapping one another, you should get a reading of 1.2nF.

The radius of each plate is 6 inches.  There are 6 top plate surfaces.  Each of the top plates are a 180 degree of a circle and have areas of 58 sq inches.  The Range of Capacitance we have been able to achieve with this design is C = 0 to 1.2nF.

ExportableNo
Demo on DimeNo
PIRA 200No
Export Instructions (if different)
HazardsNone
Analysis/Information

​Capacitance is the ability of a body to store an electrical charge.  The higher the capacitance, the more electric charge can be stored at a given voltage.  Any object that can be electrically charged exhibits capacitance, however the concept is particularly important for understanding capacitors. 

A parallel-plate capacitor, consisting of two or more conductive plates insulated from each other, usually sandwiching a dielectric material.  Capacitance is directly proportional to the surface area of the conductor plates and inversely proportional to the separation distance between the plates.  Capacitance is C = q/V.

The capacitance is a function only of the geometry of the design (area and distance between) and the permittivity of the dielectric material between the plates of the capacitor.  Parallel-plate capacitor C = epsilon*A/d

Category5 Electricity and Magnetism
Subcategory5C - Capacitance
Keywordsvariable capacitor
Construction Information
 
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capacitor - variable parallel plate
1
multimeter - voltage DC
1
banana cable
2
camera - b&w
1