Electrostatics

PIRA classification 5A

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

Please note that Not All of these tables have 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.

5A10. Producing Static Charge

PIRA #	Demonstration Name	Subsets	Abstract
5A10.00	Flamingo and Bag
5A10.01	peizoelectricity		see 5E60.20
5A10.10	rods, fur, and silk	pira200	PVC rod and felt, acrylic rod and cellophane, and rubber rod with wool. An Electroscope can be used as a charge indicator.
5A10.11	separating charge		Several common ways to separate charges. Scuff a rug and then discharge through a neon bulb.
5A10.12	charge the student		Strike a student sitting on an insulated stool on the back with a fur. If the student holds a key, sparks may be drawn without discomfort.
5A10.15	triboelectric series, halos		A triboelectric series including modern polymers is listed to help in finding a way to charge yourself so you can levitate a thin metalized plastic hoop as a halo.
5A10.16	identifying charges		Use an electroscope charged with known sign to test other charged objects.
5A10.20	Electrophorus		Use a metal plate on a handle to transfer charge from a large charged surface. Repeat charging a metal plate many times. Obtaining charge by induction
5A10.21	Electrophoru, Making		Directions for making an electrophorus. from sealing wax. Use a neon discharge tube to show a flash by holding one end on the electrophorus. and then touching the other end.
5A10.22	electrophorus, etc		Four demos: one illustrating the action of an electrophorus., another showing the reaction of a charged balloon to a paddle charged positive, negative, or neutral, and more.
5A10.23	cylindrical electrophorous		A copper tube on a handle fits over a 1" polystyrene cylinder mounted vertically. Some discussion about how electricity is transferred on rubbing that contradicts standard approaches.
5A10.24	electrophorus - neon wand		A neon wand flashes as polystyrene/metal electrophorus. is opened and closed.
5A10.30	electret		Directions for making an electret. Used the same as an electrophorus. except it is permanently charged. References.
5A10.35	equal and opposite charge		Two electroscopes are charged equal and opposite, then the charge is transferred from one to the other. If tape is pulled off an electroscope plate, charge will result and the tape will also charge a second electroscope with the opposite charge. Picture.
5A10.36	equality of charges		Rub a rubber rod against a similar rod covered with wool in a Faraday ice pail. The electroscope shows no charge unless either of the rods is removed. Or, rub them together outside the pail and insert them separately and together.
5A10.37	electrostatic rod and cloth		Rub a rod with a cloth, place on a pivot, show attraction between rod and cloth. - Related to 5A20.10
5A10.40a	shake mercury in a bottle {Not Made Yet}		Put some mercury in a plastic bottle with a conducting rod sticking through a stopper. shake the mercury and invert to charge the rod for a positive charge, invert a second time for negative.
5A10.40b	mercury-glass charging wand		A glass tube containing some mercury is covered with tin foil on one end. Either positive or negative charge may be produced.
5A10.43	mercury tube		Directions for making a mercury tube that emits light when shaken. Optionally neon is introduced to produce more light.
5A10.50	cyrogenic pyroelectricity		The polarization of some pyroelectric crystals increases dramatically at low temperatures.
5A10.55	heating and cooling tourmaline		Heat a long thin crystal of tourmaline over a flame and when it cools opposite charges develop on the ends large enough to deflect an electroscope. [A long thin crystal of tourmaline that has been immersed in liquid air will form opposite charges on the ends upon warming.]
5A10.56	charge by freezing sulfur		Allow molten sulfur to solidify on a glass rod, check with an electroscope.
5A10.76	stretched rubber band		A stretched rubber band becomes charged positively. Any amount of charge can be removed by sliding along the band.
5A10.90	electrostatics in a hot box		Perform electrostatics demonstrations in a heated box to decrease the relative humidity.

5A20. Coulomb's Law

PIRA #	Demonstration Name	Subsets	Abstract
5A20.10	Stirrup	pira200	Rods and Pivot
5A20.20	Two Pith Balls		Suspend two small pith balls and show either attraction or repulsion.
5A20.20	Coulomb's law with pith balls		Charge two pith balls with an electrostatic generator, project on the wall and measure, discharge one ball, and remeasure the separation. Accuracy is typically 2%.
5A20.21	Coulomb's law on the overhead		Demonstrate Coulomb's law on the overhead with two ping-pong balls. Suspend two pith balls coated with Aquadag in a clear framework on the overhead projector.
5A20.22	hollow aluminum foil balls		Hollow aluminum foil balls are charged with a Van de Graaff generator. Metal painted ping pong balls, gas filled balloons, pith balls are used as charge indicators. Or Packing Peanuts
5A20.23	Cylinder and Balls		A small charged pith balls are repelled from a charged cylinder .
5A20.24	electric potential		Bring a charged pith ball close to a like charged conductor and note the repulsive force.
5A20.25	Electrostatic ping-pong deflection		Attraction and repulsion between charged conductive ping pong balls. Two silver coated ping pong balls are suspended from separate supports.
5A20.26	ping pong ball electroscope		Details of an electroscope made with ping pong balls on the ends of hanging rods.
5A20.27	image charge{Must Buil		A large metalized styrofoam ball is mounted on a rod with a counterwieght and air bearing at the midpoint. Bring a second ball and then a highly charged metal plate near. [Polystyrene spheres (3" dia.) are mounted on counterweighted Lucite rods.]
5A20.28	beer can pith balls		Aluminum beer cans are used instead of pith balls to show repulsion of like charges.
5A20.30	Myar balloon repulsion		Balloon electroscopes, helium filled or normal, can be painted with aluminum and charged with a Van de Graaff. or Hang an aluminized balloon is hung from a rod attached to the Van de Graaff electrode to demonstrate repulsion of like charges. or Tape mylar balloons on conducting strings to a Van de Graaff generator.
5A20.35	Coulomb's law balance		The PSSC soda straw balance is adapted to make a simple Coulomb's law balance.
5A20.40	aluminum sheet electroscope		Two squares of aluminum foil are suspended from wires across a glass rod.
5A20.41	large leaf electroscope		A 15" length of 1 1/2" mylar tape is suspended along a brass strip.
5A20.50	measuring Coulomb's law		An optical lever and damper make this apparatus useful to demonstrate Coulomb's law. Diagram, Construction details in appendix, p. 1311.

5A22. Electrostatic Meters

PIRA #	Demonstration Name	Subsets	Abstract
5A22.10	Leybold Braun electroscope		Show the Leybold Braun electroscope with some other electrostatics apparatus. A Leybold Braun electroscope is a well balanced needle with can measure voltages to a few KV.
5A22.12	Electroscopes and Electrometers		The Braun electrostatic voltmeter and Zeleny oscillating-leaf electroscope are described and pictured.
5A22.22	Electroscopes		Show different types of electroscopes.
5A22.25	Pop-can-tab Electroscope	pira200	The tabs off of two popcans supports charge like that of the leaves within an electroscope.
5A22.26	leaf electrometer		Modify a leaf electroscope so it discriminates polarity of charge.
5A22.30	Leaf Electroscope		A leaf electroscope is projected with a point source or show with a camera. Use changing materials to show changes.
5A22.41	vibrating reed electrometer		Circuit diagram for a vibrating reed electrometer. Ten demonstrations using the device are listed.
5A22.45	oscillating electroscope		An insulated indicating wire is charged by corona and rises until it touches a ground, then the cycle repeats.
5A22.50	Kelvin electrostatic voltmeter		A rotating vane electrostatic voltmeter.
5A22.51	electrostatic voltmeter		Measure voltage with a rotor and vane electrostatic voltmeter. Picture, Construction details in appendix, p.1320.
5A22.60	condensing electroscope		Charges too small to be detected by an electroscope can be detected with the addition of a variable capacitor. Directions and a drawing.
5A22.65	electrometer with concentric cap.		Concentric capacitors are mounted on an electrometer with the outer grounded. Insert samples in the inner to measure charge.
5A22.70	Pasco equipment		A Pasco electrometer along with the whole kit of Pasco accessories.
5A22.71	Pasco projection meter		A remote projection meter for the Pasco electrometer.
5A22.80	electric field mill		Contains short explanation of an instrument used to measure the electric field.
5A22.81	simple field mill		A circuit used in a simple field mill.
5A22.90	electroscope on a diode tube		An aluminum foil electroscope attached to the plate of a rectifier diode tube is discharged when the power is turned on.
5A22.91	triode electroscope relay		An antenna is hooked to a grid of a triode tube that controls a relay turning on a light bulb. Charged rods brought close to the antenna turn the light on or off.
5A22.95	negative charge detector		The neon light goes out in a triode circuit when negative charge is brought close to a wire connected to the grid.

5A30. Conductors and Insulators

PIRA #	Demonstration Name	Subsets	Abstract
5A30.10	wire versus string		Connect two electroscopes together with wire, string, or silk thread and charge one electroscope. show the difference in conductivity
5A30.15	conductors and insulators		Aluminum and acrylic rods are mounted on a Braun electroscope. Bring a charged rod close to each rod.

5A40. Induced Charge

PIRA #	Demonstration Name	Subsets	Abstract
5A40.10	charging by induction	pira200	Charging by induction using two balls on stands with an electroscope for a charge indicator.
5A40.12	induced charge		Use electroscopes and proof planes to show charging by induction.
5A40.13	methods of electrostatic induction		Various forms of conductors are separated in an electric field.
5A40.15	electroscope charging by induction		Use conductors on the top of two electroscopes that can be brought into contact to demonstrate charging by induction.
5A40.15	induction charging		Large metal bars on two electroscopes are apart when charging by induction.
5A40.16	charging electroscope by induction		Touch the plate of an electroscope while holding a charged rod nearby. Next month may contain answers to impertinent questions raised by high school students.
5A40.16	charging electroscope by induction		Answer to the question of an earlier Physics Teacher. Diagrams show how an electroscope is charged when touched while a charged rod is brought near.
5A40.16	charging electroscope by induction		Charge an electroscope by touching while holding a charged rod near.
5A40.17	electrostatic charging by induction		Pith balls touching both ends of a conductor are charged when a charged rod is brought toward one end. Use another test charge to show the polarity at each end.
5A40.20	can attracted to charged rod	pira200	A hoop of light aluminum is attracted to a charged rod.
5A40.23	charged ball attracted to ground		A metalized ball is attracted to a grounded aluminum sheet when a charge is applied to the ball.
5A40.23	suspended electrophorus disc		Raise an electrophorus. disc off the plate with a helical spring, touch the disc to remove induced charge, and show the spring lengthens.
5A40.24	blow soap bubbles at Van de Graaff		Blow neutral soap bubbles at a Van de Graaff generator for intriguing induction effects. Try double bubbles.
5A40.25	paper sticks on the board		Hold a piece of paper on a slate blackboard and rub it with fur.
5A40.25	rub paper		Rub paper with cat fur while holding it on the board.
5A40.26	familiarity breeds contempt		Cork filings are first attracted to a charged rod by induced charge, then repelled as they become charged by conduction.
5A40.30	2" x 4"		Induced charge is used to move a 2x4 balanced on a watch glass.
5A40.30	conductivity of a "two by four"		Rotate a 2x4 by bringing a charged rod close.
5A40.30	wooden needle		The "needle" is a six foot 2X4.
5A40.35	metal rod attraction		Place a metal rod on a pivot and show attraction to both positive and negative charged rods.
5A40.36	forces between electrodes		A ball on a flexible rod is attracted to an electrostatic generator by the induced charge.
5A40.40	deflection of a stream of water		A charged rod deflects a stream of water.
5A40.40	deflection of a water stream		A charged rod is held near a stream water flowing from a nozzle.
5A40.42	deflection of water stream		At different ranges the water stream 1) the jet is smooth from nozzle to sink, 2) is attracted to the rod, 3) breaks up into small drops.
5A40.43	Raleigh fountain		A charged rod held near a stream of water directed upward breaks it into drops.
5A40.60	electrostatic generator principles		Same as AJP 37(10),1067.
5A40.60	electrostatic generator principles		Manipulate two metal cans and move a metal ball back and forth to show how charging by induction and charge transfers build up charge.
5A40.60	electrostatic generator principles		Two cans and two balls and cross your hands.
5A40.70	Kelvin water dropper		Sparks are produced by falling water.
5A40.70	Kelvin water dropper		Sparks are produced by water falling through two rings connected by an "x" arrangement to opposite receivers.
5A40.70	Kelvin water dropper		A simple Kelvin water dropper made with shower heads enclosed in cans. Diagram.
5A40.70	Kelvin water dropper		Explanation of and directions for building a Kelvin water dropper. Picture, construction details in appendix, p.1311.
5A40.70	Kelvin water dropper		A diagram and some construction details are given for the Kelvin water dropper. A "dry water dropper" using steel balls is mentioned.
5A40.70	Kelvin water dropper		A Kelvin water dropper discharges a small neon lamp. Animation sequence shows principles of operation.
5A40.72	Kelvin water dropper - ac		The Kelvin water dropper is extended to multiphase, multifrequency operation by considering N streams and N cans. A five can version is shown.
5A40.73	almost Kelvin water dropper		Water drops through a paraffin coated funnel into a brass cup. The funnel and cup are connected to a electroscope.

5A50. Electrostatic Machines

PIRA #	Demonstration Name	Subsets	Abstract
5A50.05	electrostatic generators		General discussion of electrostatic machines.
5A50.10	Wimshurst machine		An explanation of how the Wimshurst charges by induction.
5A50.10	induction generator		Shows Wimshurst machine. Animation sequence shows principles of operation.
5A50.11	Wimshurst machine		Picture of a small Wimshurst machine.
5A50.12	ac Wimshurst		The Wimshurst design is extended to produce three phase ac at 18 kV and 2 Hz.
5A50.15	Toepler-Holtz machine		A large antique Holtz machine used to generate high voltages for old X-ray machines. Will produce a 10" spark.
5A50.16	two-inductor electrostatic generator		A Wimshurst type generator simplified with only one disk for pedagogical purposes. The references for this article are found in AJP 51(9),861.
5A50.17	fur and record generator		A series of pictures illustrate construction of a simple electrostatic generator built using a hand drill, LP record, and fur.
5A50.20	dirod electrostatic machine		A rotating electrostatic machine made with a disk and rods. Picture, Diagrams, Construction details in appendix, p. 1312.
5A50.30	Van de Graaff generator	pira200	Show sparks from a Van de Graaff generator to a nearby grounded ball.
5A50.30	Van de Graaff		Design of a good size Van de Graaff.
5A50.31	Van de Graaff theory		A note on the theory of the Van de Graaff.
5A50.31	electrostatic generator		A very practical article covering theory, maintenance, and belt fabrication.
5A50.31	electrostatic generator		An explanation of the Van de Graaff generator.
5A50.31	Van de Graaff generator		Shows a Van de Graaff with paper streamers, then a long animated sequence on the principles of operation.
5A50.32	Van de Graaff vs. Simon		Theories of Van de Graaff and Simon (AJP 22,318 (1954)) are compared and experiments yield results in accordance with the Simon theory.
5A50.34	improvements to toy Van de Graaff		Double the length of the spark with two modifications.
5A50.34	improvements on the toy Van de Graaf		Two improvements to the toy Van de Graaff generator.
5A50.50	Franklin's electrostatic motors		Models of Franklin's first two electric motors are shown.
5A50.51	electrostatic motor		A polyethylene bottle spins as a Wimshurst is connected to brushes alongside the bottle.
5A50.52	electrostatic motor		A motor operated by electrostatic charges drawn from an electrostatic generator. Picture.
5A50.52	electrostatic motor		Use a large static machine to drive a smaller one as a motor.
5A50.53	elecrostatic motor		An electrostatic motor with a vane type rotor.
5A50.55	atmospheric electric field motor		Report on the construction of an electret type and corona type motor for operation from the earth's electric field.
5A40.60	electrostatic generator principles		Manipulate two metal cans and move a metal ball back and forth to show how charging by induction and charge transfers build up charge.
5A40.60	electrostatic generator principles		Two cans and two balls and cross your hands.
5A40.70	Kelvin water dropper		Sparks are produced by falling water.
5A40.70	Kelvin water dropper		Sparks are produced by water falling through two rings connected by an "x" arrangement to opposite receivers.
5A40.70	Kelvin water dropper		A simple Kelvin water dropper made with shower heads enclosed in cans. Diagram.
5A40.70	Kelvin water dropper		Explanation of and directions for building a Kelvin water dropper. Picture, construction details in appendix, p.1311.
5A40.70	Kelvin water dropper		A diagram and some construction details are given for the Kelvin water dropper. A "dry water dropper" using steel balls is mentioned.
5A40.70	Kelvin water dropper		A Kelvin water dropper discharges a small neon lamp. Animation sequence shows principles of operation.
5A40.72	Kelvin water dropper - ac		The Kelvin water dropper is extended to multiphase, multifrequency operation by considering N streams and N cans. A five can version is shown.
5A40.73	almost Kelvin water dropper		Water drops through a paraffin coated funnel into a brass cup. The funnel and cup are connected to a electroscope.

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