Today, let’s take look at a popular multi-function demonstration apparatus: The Shive Wave Machine. You can see it in action in this new video featuring Prof. Peter Shawhan.
Invented in 1959 by Dr. John Shive, a Baltimore native who became a physicist at Bell Labs, the Shive Wave Machine consists of a series of heavy steel rods connected at their centers by a stiff wire; it functions like a torsional spring. You can create a pulse by gently moving the rod at one end up and down; then you can see how the pulse propagates as a wave along the length of the wire, watching each rod move in turn. Our demonstration collection has two such devices; one has longer rods, the other has shorter rods; as you can see in the video, the different weights thus give them different transmission speeds and impedances.
This can be used to demonstrate a variety of wave phenomena. Read more about using the Shive Wave Machine to demonstrate the physics of waves, a torsional wave machine simulator, and how to build your own at home here!
One of our most popular electromagnetism demonstrations is J6-01: Electromagnet With A Bang! We discussed this demonstration in a previous highlight article. But now, you can see it in action in this new video with Landry Horimbere.
A massive block of steel is suspended by an electromagnet, courtesy of a single D-cell flashlight battery. When the switch is flipped to open the circuit, the electromagnet turns off, and the block falls dramatically to the table.
The operation of an electromagnet is based on the discovery that an electrical current generates a magnetic field as it flows through a conductor. By grouping many conductors together in a coil, arranged so that their fields align, we can sum their individual electromagnetic fields into a much stronger one. Thus, we can create a strong electromagnet even from a relatively weak current.
You can also try this out at home and in the classroom with this updated magnet simulator from the PhET collection at the University of Colorado.
The simulator has both permanent magnet and electromagnet options. Flip to the electromagnet tab; you should see, as in the screencap above, a battery connected to a coil, with many magnetic field indicators all around. Controls in the margin let you adjust the number of loops in the coil, and a slider lets you vary the voltage. Both the large magnetic compass and the magnetic field meter can be dragged around the screen to measure at different points. You can also swap the battery out for an AC power supply. Try it out!
The Lecture Demonstration Facility at the University of Maryland is designed to help faculty spark student interest, identify misconceptions, help students make predictions, facilitate discussion, and reinforce curricular concepts.
We’re often asked how many demonstrations we have in the collection. That’s a more complex question than it might at first seem.
At last count, we have just over 1,500 demonstrations published to the website – that is, that’s how many demonstration pages exist in the collection. But some pages describe a single setup than can be used in several different ways. Take a look at K2-61: Thomson’s Coil, for example. This single page actually describes four different, related demonstrations that can be performed with this device. They don’t require very different equipment to be delivered, just slight changes in preparation, though, and they’re usually all relevant at approximately the same point in a syllabus, so it’s simpler to list them all in one place. Conversely, there are many demonstrations that use the Optical Board – browse through section L and you will see many of them! Since ray optics is divided into several sections in the demonstrations catalog, each of the configurations of the Optical Board is listed separately, to make it easier to find the one you need; and if you’re only doing one demonstration with it, we can configure it for you in advance to save you time in class.
On the other hand, consider M1-12 and H2-22. These are both listings for Interference Transparencies, a popular way to illustrate the interaction of wavefronts. Here, we made the unusual decision to list the same demonstration twice in two different sections, since otherwise someone planning a course on sound might not think to look for relevant demonstrations in the optics section, and vice-versa. These occasional cross-references make it easier to find the demonstrations you need for your class.
And even aside from the demonstration listings as they stand, we’re often called on to combine equipment in unique ways to demonstrate something new! If it’s a combination that’s likely to be repeated or that proves useful to others, it will be added to the website, but we’re generally open to creatively reinterpreting demonstrations to fit a new class context.
Every year we add more demonstrations to the collection; and occasionally a demonstration is retired, if it no longer meets an instructional need or has been superseded by others. So defining just how many demonstrations we have might not be the right question to ask. Ask, rather, what can we demonstrate for you today?
Science is all about data, and our current pandemic is no different.
Be sure to check the UMD COVID-19 Dashboard for the latest campus data and links to reopening plans and proper safety procedures.
In support of most classes moving to an online model this year, the Lecture-Demonstration staff are doing our part to help connect you to resources you need for teaching remotely. As one part of this project, we have begun compiling a Directory of Simulations from around the internet, organized by general area of physics. Find it under the Tools and Resources menu above, or click the image below.
There are a tremendous number of simulations out there, that folks have been creating for years. We’re testing them out, choosing ones that we can confirm currently work (always a question as internet technology marches on) and that seem useful for our department’s classes. As of this posting, we have just over fifty simulations collected. Our initial focus has been on physics that is hard to demonstrate in the classroom, or experiments that are difficult to present as static pictures or live video.
This project is ongoing! As we continue to explore we will be adding more subjects and more demonstrations per subject. We also invite recommendations! If you have a favourite simulation, let us know (email lecdemhelp at physics.umd.edu) so we can check it out and add it to the directory.
We’ll have more new projects posted soon; watch the site for news!
As the COVID-19 pandemic continues, researchers at UMD and around the globe continue to try to better understand the virus and how to treat it.
In our ongoing work to support remote teaching, we are pleased to announce a new resource. Over the summer of 2020, a Teaching Innovation Grant helped to create our new Demonstration Videos. These can be used for remote, hybrid, and in-person classes to present demonstrations in conjunction with class engagement questions.
Every year, we host an outreach event as part of the Maryland STEM Festival, a statewide event celebrating the sciences. This year, we’re hosting virtual workshops on October 24th&25th to build and test a Vortex Generator physics demonstration. Advance registration is required; read more at the Maryland STEM Festival website!
Be sure to check out all of the other exciting events around the state throughout the month at https://marylandstemfestival.org/
Last year, Maryland Physics hosted the Maryland STEM Festival event: FLIGHT! Read more about it here.
New Date! CU2MIP 2021 January 8-10
Check out the latest blog posts!