Demos B - Demonstration ideas for teaching physics and physical science.

Demonstrations
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Mechanics
Fluids
Heat
Waves & Sound
Light
Electricity & Magnetism
Modern Physics
Chemical Reactions

Electricity & Magnetism

An electroscope is constructed from a pop can taped to a styrofoam cup. Thin strips of aluminum foil are hung from the pull tab. Electically charged objects can then be introduced and studied. .
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45. Charging by Induction
A charged ebony rod is placed in proximity to an electroscope. The induced charge causes the leaves to separate.
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46. Coulomb's Fountain
Van de Graff Fountain A Styrofoam cup, half-filled with puffed rice, is placed on top of a Van de Graff generator. When the generator is turned on a fountain of charged particles is made.
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47. Oersted's Discovery
Oersted The current generated by the Genecon generator creates a magnetic field that interacts with the compass needle.
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48. Lenz's Law
A neodymium magnet is dropped into a copper pipe. The falling magnet (changing magnetic field) induces a current that circulates through the copper pipe. The direction of the induced current is such that the induced magnetic field opposes the change in magnetic field of the falling magnet. The magnet floats in mid air.
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49. Capacitance
The electrical energy generated by the Genecon generator can be stored in a 1 Farad capacitor, and then be used to perform short term tasks.
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50. Transformer

The voltage generated by a Genecon generator (~6 V) can be stepped up sufficiently to light a 60 V Neon lamp using a buzzer and a 1:10 step up transformer.
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51. Speaker

A coil, made from magnet wire, and a magnet are taped to the bottom of a plastic drinking cup. When a hand generator is hooked up to the coil, the fluctuations in the generator current can be heard.
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52. Gauss' Law

Place a florescent light source next to a radio tuned to a weak AM station. Once a wire cage is placed over the radio the static will go away.
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53. Force on a Current Carrying Wire I
EMforce A thin 70 cm long strip of aluminun foil is taped at both ends to a stand. Applying a current (8 V) to the loop causes the foil to repel.
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54. Force on a Current Carrying Wire II
EMforce A thin 70 cm long loop of aluminun foil is taped to a stand. Applying a current (8 V) through the loop causes the foil to attract.
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55. "Magic" Motor***NEW!***
Magic Motor A neodymium disc magnet is suspended from the positive end of a 1.5 V battery with a wood screw (or nail). When current is applied to the side of the magnet, with a wire from the negative end of the battery, the magnet spins with high angular speed.
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56. Mystery Motor ***NEW!***
A neodymium sphere magnet is suspended between the points of two wood screws. As current passes from the side of the magnet to the bottom, the magnet spins.
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57. Generator Efficiency
genecon The efficiency of genecon generators can be compared by hooking twotogether, and calculating the ratio of input turns to output turns.
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58. Wire Resistance
Nichrome The electrical resistance of a section of nichrome wire is shown to be a function of wire length.
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59. Magnetic Compasss
A piece of thread is tied around a neodimium magnet. The magnet rapidly aligns with the earth's magnetic field once suspended.
60. Magnetic Field Strength 1
Neodimium magnets (salvaged from an obsolete computer hard drive) are placed on either side of one's hand. The magnetic field is strong enough to hold the magnets firmly in place when seperated by the thickness of one's hand.
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61. Magnetic Field Strength 2
Neodimium magnets are strong enough to attract the trace amounts of iron in American currency.
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56. CRT "Magic"
CRT Magic Using an obsolete TV or computer monitor, the image on the screen can be displaced when a magnet is moved nearby. From this, one can reasonably infer that the magnet is deflecting the electron beam inside the picture tube.
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ModernPhysics

62. Solid State Electronics

A light-emitting diode is connected in series with a 200 ohm resistor to a three volt source. The one-way nature of conduction is then shown.
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63. The Peltier Effect
Peltier The absorption or emission of heat energy when electrons move from one state to another across dissimilar semiconductor junctions is known as the Peltier effect. Connect the Genecon generator to a commercially available thermoelectric device. Turn the handle one way, and the plate heats up. Reverse direction, and the plate cools down.
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64. Quantum Numbers
Quantum An analogy between the number of turns in a Mobius strip and the principle quantum number can be made. The analogy can also be extended to the DeBroglie wavelength.
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Chemical Reactions

65. Latent Heat of Fusion

A clear plastic pouch of sodium acetate releases latent heat upon crystalization.
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66. Synthesis of a Compound
When two or more elements combine to form one compound, it's known as a synthesis reaction.
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67. Decomposition of a Compound
When one compound breaks apart into two or more atoms, it's known as a decomposition reaction.
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68. Single Replacement in a Compound
When one atom takes the place of another in a compound, it's known as a single replacement reaction.
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