## Resistance

PIRA classification 5D

 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.

# Resistance Characteristics

 PIRA # Demonstration Name Abstract 5D10.10 resistor assortment 5D10.11 scaled up resistor box Rebuild an old resistance box with larger numbers. 5D10.20 characteristic resistances Connect one meter lengths of various wires in series and measure the voltage across each. 5D10.20 characteristic resistance Measure voltages on a commercial board with seven one meter lengths of various wires is series so all carry the same current. 5D10.20 resistance wires Place 6V across a set of wires of different lengths and/or diameters and measure the currents. 5D10.22 resistance characteristic of arc Measure the current and potential across a small arc as the series resistance is varied. 5D10.40 resistance model Balls are rolled down an incline with pegs. 5D10.40 model of resistance A ball is rolled down a board with randomly spaced nails. 5D10.40 charge motion demonstrator Small balls are rolled down a board with nails scattered in an almost random pattern. Diagram. 5D10.40 electron motion model Ball bearings are simultaneously rolled down two ramps, one with pegs and one without. 5D10.50 current model with Wimshurst

# Resistivity and Temperature

 PIRA # Demonstration Name Abstract 5D20.10 wire coil in liquid nitrogen A lamp glows brighter when a series resistance coil is immersed in liquid nitrogen. 5D20.10 resistance at low temperature A lamp glows brighter when a series resistance coil is immersed in liquid air. 5D20.10 cooled wire A copper coil in series with a battery and lamp is immersed in liquid nitrogen. 5D20.11 resistance at low temperature A "C" battery, 3 V flashlight bulb, and a copper wire coil make a hand held temp coefficient of resistivity apparatus. 5D20.12 audible temp-dependent resistance The resistor plunged into liquid nitrogen is part of a voltage controlled oscillator that drives a speaker. 5D20.12 cooling Current is increased in a long U of iron wire until it glows, then half is inserted into a beaker of water. 5D20.14 superconducting wire Cool a coil of NbTi wire in a series circuit with a 12 volt car battery and lamp first in liquid nitrogen, then helium. The voltage across the coil is monitored and the lamp brightness is observed. 5D20.15 flame and liquid nitrogen Resistance coils are heated and cooled with a test light bulb in series. 5D20.15 temperature dependence of resistance Two sets of bulbs in series with coils, one put in liquid nitrogen and the other in a flame. 5D20.16 temperature coefficent of resistance Two coils of different material but the same resistance are placed in a Wheatstone bridge and either is heated or cooled. 5D20.20 iron wire in flame Heat a coil of iron wire in series with a battery and a lamp and the lamp will dim. 5D20.20 iron wire in a flame A coil of forty turns of iron wire is heated in a flame while connected in series with a light bulb circuit. 5D20.20 putting the light out by heat A coil of iron wire wound on a porcelain core in series with a lamp and battery is heated until the lamp goes out. 5D20.20 heated wire Heat a coil of iron wire in series with a battery and a lamp. 5D20.21 flame A coil of nickel wire connected to a battery and galvanometer is heated in a flame. 5D20.30 pos and neg resistance coefficients Measure current and resistance at various voltages for a carbon and tungsten bulb. 5D20.30 carbon and tungsten lamps Plot current vs. voltage for carbon and tungsten lamps. 5D20.31 resistance of light bulbs The V/I curves for tungsten and carbon filament lamps are shown on a dual trace storage oscilloscope. 5D20.32 temperature of incandescent lamps Two silicon solar cells with interference filters measure the light at different wavelengths for use in determining the temperature of the filament. 5D20.40 resistance thermometer Attach No. 14 copper leads to a platinum coil and use with a Wheatstone bridge. 5D20.50 thermistors Use a good kit of commercial thermistors and display the differential negative resistance of a fast thermistor on a transistor curve tracer. 5D20.50 thermistor Show the resistance of a thermistor placed in an ice water bath. 5D20.60 conduction in glass at high temp A simple version of glass conduction using binder clips and window glass. 5D20.60 conduction in glass at high temp Heat a capillary tube in a Bunsen burner until it is hot enough to sustain a current that maintains a bright glow. 5D20.60 conduction in glass Heat a glass tube with a flame until it is hot enough to sustain conduction. Vary the current by changing the ballast resistance. 5D20.61 negative temp coeff of resistance A Nerst glower must be heated with a flame until the resistance is low enough to sustain electrical heating.

# Conduction in Solution

 PIRA # Demonstration Name Abstract 5D30.10 conductivity of solutions Dip two metal electrodes in series with a light bulb in various solutions. 5D30.10 conduction thru electrolytes Immerse two copper plates in series with a lamp in distilled water, add barium hydroxide, then sulfuric acid. 5D30.10 conduction thru electrolytes Put two copper plates in series with a lamp in distilled water and salt or acid is added. 5D30.10 conductivity of solutions Two electrodes in series with a 110 V lamp are dipped into distilled water, salt water, a sugar solution, a vinegar solution, and tap water. 5D30.13 salt water string 5D30.15 electrolytic conduction on chamios Suspend a chamois between ringstands, show no conduction with a battery, resistor, meter. Soak in distilled water, repeat, then sprinkle on salt 5D30.20 speed of ions Show KMnO4 migrating with current towards the positive electrode in KNO3. 5D30.20 migration of ions Permanganate ions migrate in an electric field. 5D30.21 ionic speed Dip two platinum electrodes into an ammoniated copper sulfate solution containing some phenophthalein. 5D30.22 ionic speed Blue moves from the anode of in a potassium chloride gel when 120 volts is applied. 5D30.23 ionic speed Measuring the speed of hydrogen and hydroxyl ions in a potassium chloride gel. 5D30.30 pickle glow

# Conduction in Gases

 PIRA # Demonstration Name Abstract 5D40.10 Jacob's ladder A arc rises between rabbit ear electrodes attached to a high voltage transformer. 5D40.20 conduction of gaseous ions A nearby flame will discharge an electroscope. 5D40.21 discharge with flame A flame connected to a high voltage source is inserted between charged parallel plates. 5D40.25 blowing ions by a charged plate Compressed air blows ions from a flame through the area between charged parallel plates onto a mesh hooked to an electrometer. 5D40.25 discharge by ions in a tube Electrodes at the bottom, middle, and top of a tube are connected to an electrometer while a Bunsen flame is burned at the bottom. 5D40.27 recombination of ions Ions from a flame are drawn past a series of charged plates attached to a Zeleny electroscope. 5D40.28 separating ions from flame Shadow project a flame between two charged metal plates to observe separation of gas into two streams of oppositely charged ions. 5D40.30 ionization by radioactivity Discharge an electroscope with a radioactive source. 5D40.32 ionization in air Various sources of ionization are brought near parallel wires attached to a 100 V battery and a Zeleny electroscope. 5D40.33 saturation The voltage across a plate close to a wire mesh is increased with a radioactive source nearby and the current is observed with a Zeleny electroscope. 5D40.34 ion mobilities A second mesh is inserted into the apparatus of A-2 and an alternating potential increased until the electroscope oscillates. 5D40.35 conduction in air by ions An electrometer measures the current between parallel plates as a flame is burned between them or an alpha source is held nearby. 5D40.36 Cerberus smoke detector Combustion products decrease conductivity in a chamber with an alpha source. 5D40.40 conduction from hot wire A constantan wire held near a charged electroscope causes discharge when it is heated red hot. 5D40.41 thermionic effect in air A Zeleny electroscope indicates electron emission from a wire when it is heated. 5D40.42 thermionic emission A commercial tube. Apply 90 V forward and reverse and monitor the current. 5D40.50 neon bulb resistivity A neon lamp lights at about 80 V and shuts off at about 60 V. 5D40.80 ionization by X-rays Discharge an electroscope with X-rays. 5D40.80 x-ray ionization Discharge an electroscope with x-rays. 5D40.81 ionization by X-rays An X-ray beam is passed through a simple ionization chamber. 5D40.99 electrohydrodynamics read this again - practical examples are ink jet printing and electrically driven convection.