PIRA Code(s): 1D60.20 Set up time:5 minutes Operation: Mount apparatus to ring stand using clamp, adjust until apparatus is horizontal, cock the apparatus spring, and place the masses (one at the end of the apparatus and one on the bar that extends from the apparatus), release, and one ball will fall from rest (hung on the rod) while the other ball is struck by the rod and has an initial horizontal velocity. The balls should hit the table at the same time, which can be heard clearly by students. Repeat by cocking spring to different compression. Repeat by clamping apparatus at a different height to show that height has no effect on the simultaneity of the fall. Physics and Science Concepts: Projectile Motion Safety: Once spring is compressed, do not put hands in front of the end of the rod.
PIRA Code(s): 1M40.20 Set up time:none Operation: Place ball at the top of track and let it fall. To show students the minimum height required to loop the loop, place the ball on the track at a height that is about double the height of the loop. Physics and Science Concepts: Mechanics, Work and Energy, Conservation of Energy, Centripetal Force Safety: Do not stand where the ball exits the track.
PIRA Code(s): 5A20.20 Set up time:1 minute Operation: Charge the rod by rubbing it the through the cloth provide or on your shirt. Hold the rod near a pith ball. The two balls will repel each other. The PVC gives a positive charge and the acrylic rod gives negative charge. Physics and Science Concepts: Electrostatics, Coulomb’s Law Safety: None
PIRA Code(s): 5A50.10 Set up time:2 minutes Operation: Place the four (two large, two small) balls on the poles in the front about 1 inch apart. Turn the crank. Physics and Science Concepts: Electrostatics Safety: Do not touch any metal portions of the generator
PIRA Code(s): 5A50.30 Set up time:10 minutes Operation: Plug in the generator. Turn on the rocker switch and adjust speed using potentiometer on the base of the Van de Graaff.
Other suggested uses include combining this with other electrostatic demonstrations found under a 5A50 heading. Also, throwing packing peanuts or taping strips of paper to the Van de Graaff are popular demonstrations. Physics and Science Concepts: Static Electricity, Friction Safety: The rod works best on dry days with the blue wig. Care should be taken when operating. Do not approach the generator while it is running. Use the grounding rod to discharge.
PIRA Code(s): 5B30.20 Set up time:5 minutes Operation: Use the Van der Graaf or Wimshurst generator to charge the ovoid. Touch a proof plane to the pointed end of the ovoid and another to the spherical end. Place the proof planes on the electroscope plate. The deflection will be greater from the proof plane that touched the pointed end. Physics and Science Concepts: Electrostatics, Surface Charge Density Safety: Electroscope can be obtained from demonstration number 5A22.22.
PIRA Code(s): 5C10.20 Set up time:none Operation: Charge the plates using the Van de Graaff. Disconnect wire going from top of sphere to fixed plate at plate end. Change the spacing of a charged parallel plate capacitor while it is attached to an electroscope. Observe changes in electroscope pointer. Physics and Science Concepts: Capacitance Safety: Electroscope can be obtained from demo 5A22.22. The Van de Graaff can be obtained from demo 5A50.30.
PIRA Code(s): 5E40.20 Set up time:1 minute Operation: Pour sulfuric acid into the glass container. Wait 5 minutes for the reaction to take place between the dissimilar metals. Place the voltmeter on the overhead and display the voltage generated in the cell. Physics and Science Concepts: Electromotive Force and Current Safety: Be careful around acid. Gloves and goggles should be worn when handling acid.
PIRA Code(s): 5K10.20 Set up time:1 minute Operation: Hook the leads from the galvanometer to the induction coil. Place a magnet in front of the coil. Turn the crank and the needle on the galvanometer should move. The connection between the galvanometer and the loop changes polarity every half turn. Physics and Science Concepts: Electromagnetic Induction, Electricity and Magnetism Safety: Magnet is extremely strong so do not place metal objects near it.