## Capacitance

PIRA classification 5C

 Grayed Demos are either not available or haven't been built yet

Please note that these tables have not yet been edited to match the equipment that is available within the UW-Madison lecture demo lab. There maybe many items listed within these tables that we either "can not do" or have available.

# 5C10. Capacitors

 5C10.10 sample capacitors Show many capacitor examples. 5C10.15 simple spherical capacitor Charge a 8" sphere several times with an electrophorus, then repeat with a insulated conductor near, then repeat with a grounded conductor near. The number of sparks required to reach a potential varies. 5C10.20 field and voltage Vary the spacing of a charged parallel plate capacitor while the voltage is measured with an electroscope. 5C10.21 battery and separable capacitor Charge a parallel plate capacitor to 300 V, then move the plates apart until an electroscope deflects. 5C10.30 dependence of capacitance on area As a chain is lifted out of a hollow charged conductor on an electroscope, the deflection decreases. When let back down, it increases again. 5C10.31 dependence of area on capacitance A long rectangular sheet of charged tin foil is rolled up while attached to an electroscope. 5C10.32 dependence of capacitance on area Hook up a charged radio tuning condenser to an electroscope. 5C10.33 Chinese lantern capacitor Vary the length of an aluminum painted Chinese lantern to show the change of capacitance. 5C10.35 rotary capacitor Charge a large rotary capacitor with a rod and watch an electroscope as the overlap is changed. 5C10.40 C=i/(dv/dt) demonstrator Vary a potentiometer so that a constant current is maintained while charging a capacitor from a 90 volt battery. Measure the time. 5C10.50 inducing current with a capacitor A charged ball moving between the plates of a parallel plate capacitor will induce a current in the external circuit.

# 5C20. Dielectric

 5C20.10 capacitor with dielectrics The voltage is measured with an electroscope as dielectrics are inserted between parallel plates of a charged capacitor. Various dielectrics are inserted between two charged metal plates to show the difference in deflection on an electroscope. 5C20.11 capacitor with dielectrics Six demonstrations with a parallel plate capacitor and dielectrics. 5C20.12 equation Q=CV The bottom of a parallel plate capacitor is mounted on an electroscope, charge the top plate, touch the bottom, lift off the top. 5C20.13 C-V relationships An automated device to charge a capacitor and separate the plates. Reference: AJP 22(3),146. 5C20.14 intervening medium Bring a charged rod close to an electroscope and interpose various materials between the two. 5C20.17 helium dielectric Helium is blown into a charged parallel plate capacitor. 5C20.20 force on a dielectric A counterbalanced acrylic dielectric is pulled down between parallel plates when they are charged with a small Wimshurst generator. 5C20.21 force on a dielectric - glass plate A microscope slide is pulled into the gap between parallel plates of a capacitor. 5C20.22 force on a dielectric A elongated paraffin ellipsoid in a parallel plate capacitor turns when the field is turned on, kerosene climbs between parallel plates. 5C20.25 attraction of charged plates A brass plate fitted with an insulating handle can lift a lithographic stone plate when 300 V dc is applied. 5C20.26 attraction of charged plates The top plate of a parallel plate capacitor is mounted on a triple beam balance so the force can be measured with and without dielectrics as the voltage is varied. Pictures, Construction details in appendix, p.1322. 5C20.27 attraction of charged plates The permittivity of free space is measured using a Mettler balance to determine the force between the plates of a parallel plate capacitor. 5C20.30 dissectible condenser A capacitor is charged, disassembled, passed around, assembled, and discharged with a spark. 5C20.30 dissectible condenser Same as Ed-3. 5C20.30 dissectible condenser A capacitor is charged, disassembled, passed around, assembled, and discharged with a spark. 5C20.30 dissectible condenser The inner and outer conductors of a charged Leyden jar are removed and brought into contact, then reassembled and discharged in the usual manner. 5C20.30 dissectible capacitor Charge a capacitor and show the discharge, then charge again and take it apart. Handle it, try to discharge it, reassemble it, and discharge it. 5C20.35 bound charge The two coatings of a Leyden jar can be grounded successively without much loss of charge. When the two coatings are connected, there is a discharge. 5C20.40 impedance of a dielectric Place a small parallel plate capacitor in series with a phonograph pickup. Insert different dielectrics. High dielectrics have low impedance. 5C20.50 breath figures Blow on a glass plate that has been polarized with the image of a coin. 5C20.51 Lichtenberg figures A pattern is traced on a dielectric from the two polarities of a charged Leyden jar. Litharge and flowers of sulfur sprinkled on adhere to the areas traced out with the different polarities. 5C20.60 displacement current A toroidal coil is either placed around a wire leading to a large pair of capacitor plates to demonstrate Ampere's law or inserted between the capacitor plates to demonstrate displacement current. 5C20.61 displacement current Measure the displacement current in a barium titanate capacitor. 5C20.61 displacement current comment comment More semantics. 5C20.61 displacement current comment The experiment in AJP 32,916,(1964) has nothing to do with displacement current in Maxwell's sense. 5C20.61 displacement current Measure the displacement current in a barium titanate capacitor. Diagrams, Derivation.

# 5C30. Energy Stored in a Capacitor

 5C30.10 Leyden jar Sparks from a Wimshurst are no longer but are much more intense when a Leyden jar is connected. 5C30.10 Leyden jars on Toepler-Holtz The Topler-Holtz produces weak sparks without the Leyden jars and strong less frequent sparks with the jars connected. 5C30.15 exploding capacitor 5C30.15 grounded Leyden jar Charge a capacitor with a Wimshurst, ground each side separately, spark to show the charge is still there. 5C30.20 short a capacitor Charge a large electrolytic (5000 mfd) capacitor to 120 V and short with a screwdriver. 5C30.20 short a capacitor A 5600 microF capacitor is charged to 120 V and shorted. 5C30.20 exploding capacitor Four 1000 microF capacitors are charged to 400 V storing about 320 Joules. Short them with a metal bar. 5C30.25 capacitor and calorimeter Discharge a capacitor into a resistor in an aluminum block with an embedded thermistor to measure the temperature increase. 5C30.30 light the bulb see 5F30.10 5C30.30 light a bulb with a capacitor Charge a large electroylitic capacitor and connect it to a lamp. 5C30.30 light the bulb A 5600 microF capacitor is charged to 120 V and discharged through a light bulb. 5C30.35 lifting weight with a capacitor 5C30.35 energy stored in a capacitor A capacitor is discharged through a small motor lifting a weight. 5C30.35 lifting a weight with a capacitor A DC motor lifts a weight powered by a charged capacitor. 5C30.36 discharge a capacitor thru wattmeter A high impedance low rpm dc motor (wattmeter) is used to discharge a capacitor. 5C30.37 charge on a capacitor A capacitor is discharged through a ballistic galvanometer. 5C30.37 capacitors and ballistic galv Charge different capacitors to different voltages and discharge through a ballistic galvanometer. 5C30.40 series/parallel Leyden jars 5C30.40 addition of potentials Charge Leyden jars in parallel and discharge, charge in parallel again and connect in series before discharging. Compare length and intensity of the sparks. 5C30.41 series and parallel condensers Charge four Leyden jars in parallel and discharge singly and with three together. Next charge three in series with one in parallel and discharge singly and three in series. Compare length and intensity of sparks. 5C30.42 series/parallel capacitors 5C30.42 series/parallel capacitors Charge a single capacitor, two series capacitors, and two parallel capacitors to the same potential and discharge through a ballistic galvanometer. 5C30.50 Marx and Cockroft-Walton circuits Intentionally low voltage models of the Marx generator and the Cockroft-Walton circuit allow the waveforms to be shown as a demonstration without high voltage probes or danger. 5C30.50 Marx generator Switching capacitors from parallel to series to generate high voltages. 5C30.50 Arkad'ev capacitor-bank transformer Switching of charged capacitors from parallel to series. 5C30.60 residual charge Charge and discharge a Leyden jar, Wait a few seconds and discharge it again. 5C30.61 residual charge After discharging a Leyden jar, light a neon tube up to 100 times. Also - show the polarity of charge on the dielectric with a triode.

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