Weber State University, HARBOR

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Interesting lecture demo room items that I cannot identify. If you know what it is (and even better, if you know how to use it) please send me an email:

Click on the images for a larger view.

Some notes added thanks to Sam.

Item #1: Welch Hoop. Sort of like a giant air track car bumper, about 40cm in diameter. It is somewhat flexible, again, like a giant bumper. (One person, Ron C. made the very reasonable suggestion: "I think it’s a resonance frequency demonstrator.  Plug it into a wave frequency generator and you can see standing waves in the circle as you adjust the frequency."

It seems too stiff for the standing waves demo. Perhaps it is a rotating frame of reference. Opposite the stud is a small hole that you can hang a pendulum from. If you set the pendulum to swinging then rotate the hoop, it will show that the pendulum is unaffected and continues to swing in the same plane.

01 Welch Hoop

Item #2: CENCO some sort of torque demo? If so, what are all the other blocks for? They are just blank blocks that clearly match the one with the bolt. New information makes it sound like our (late) lecture demo tech (Lenord) made this as a demo on torque and the right hand rule for screws. The other blocks might just be left over from when he made it 30 years ago.

2. CENCO some sort of torque demo?

 Item #3: Support rod? The left end clearly bolts into unistrut style frames. The "wire" is about the same diameter as 14 gauge home wiring but is stiffer. I have no idea what orientation it is supposed to be used in or for what purpose.

3. Support Rod

Item #4. Possible electrostatics demo? There is no wiring under the base, what you see is everything. The top horizontal rods are electrically isolated from the lower rods.

Electrostatics demo 1?

Item #5: Electrostatic discharge demo? I have not inspected the base to see if the metal ground plane has an insulator between it and the vertical bar with the sharp points.

Electrostatic discharge?

Item #6. Two views of a metal plate. The numbers indicate that it was once part of a introductory lab activity (those were lab station numbers as was used by the department in the 1960s and into the 1980s. Top view then bottom view.

This might be an electrophorus static charge demonstration. Here is an example from the Univ. of Rochester. The MagLab has a nice webpage on electrophorus.

Top view

Bottom view

Item #7: Sargent-Welch support system. The middle bracket is missing the spring (an easy repair if it is worth repairing). Looks like one end clamped something (a rod?) that then rested on the two springs. Two views: overall and close up of the support.

This could be a collision demonstration where you have a V-shaped track that lies on the springs and you roll two steel balls on it. I'm not convinced though, there are easier ways to do that. I think the clamp holds something like a rod and the rod rests on the springs so it can expand/contract (thermo expansion) or can vibrate.

S-W support device

S-W clamp detail

Item #8: Cork dust. Yes, yes, I know it is cork dust and that is actually what is inside the can too. The question is: what in heck do you use cork dust for in a physics lecture demo hall? (Or in a lower division lab.)

The cork dust could be used in a Kundt's tube to demonstrate sound waves and resonance inside a tube.

One of our faculty (Adam J.) uses it  "for sprinkling on water surfaces to see how much diameter an oil drop spreads, pushing the cork dust out of the way. With a really small drop (diluted in ethanol) you can get a monolayer and then calculate the thickness of the molecule."

8. Cork Dust, but why?

Item #9: Welch demo. Three views. I am beyond clueless on this one. The glass tube is bent in the form of a question mark and is open at both ends. The hole in the top (?) wood plug lines up with the center and the glass tube, but there is no connection.

This might be a Pythagorean cup.

Welch something

Welch glass something

Welch glass something, view under the cap.

Item #10: Glass tubes filled with unknown liquid. I'm wondering if this is a thermodynamics demo where you warm the liquid with your hand and it bubbles from one chamber to the other. But there doesn't seem to be enough fluid left for that to work. (I can make it do that if I'm careful about the angle I hold it at, but it isn't very impressive as a demo in that way.)

It has been suggested that these are hydrometers without scale marks. I don't think so, hydrometers are weighted at one end to force them to float in the correct orientation.

10. Glass tubes, view with hand for scale.

10. Glass tubes with hand for scale while holding.

Item #11: Cenco electrical demo. This appears to be a thermopile. You put one set of thermocouples in hot water and one set in cold water and measure the voltage from the Seebeck effect across the banana plug connectors.

CENCO wire demo

CENCO wire demo front view