Maryland Day 2025

Sheng-Wei Wang, Millicent (Milli) Ayako, and Prof. Carlos Romero-Talamás

Electromagnetism (theremin, plasma sphere)

Theremin

Hannah McCright (B.S., Physics, 2025) shows two excited, future scientists the theremin.

                Heather Pettit playing with the theremin.

 Uncle Sam testing out the theremin.

The Story of the Theremin

The theremin, originally known as the aetherphone, etherphone, thereminophone or termenvox/therminvox) is an electronic musical instrument controlled without physical contact by the performer (who is known as a thereminist).  It is named after its investor, Leon Theremin, who patented the device in 1928.  

The instrument's controlling section usually consists of two metal antennas which function not as radio antennas but rather as position sensors. Each antenna forms one half of a capacitor with each of the thereminist's hands as the other half of the capacitor. These antennas capacitively sense the relative position of the hands and control oscillators for frequency with one hand, and amplitude (volume) with the other. The electric signals from the theremin are amplified and sent to a loudspeaker.

The sound of the instrument is often associated with eerie situations. The theremin has been used in movie soundtracks such as Miklós Rózsa's Spellbound and The Lost Weekend, Bernard Herrmann's The Day the Earth Stood Still, and Justin Hurwitz's First Man, as well as in theme songs for television shows such as the ITV drama Midsomer Murders and the Disney+ series Loki, the latter composed by Natalie Holt. The theremin is also used in concert music (especially avant-garde and 20th- and 21st-century new music); for example, Mano Divina Giannone is a popular American thereminist^{[citation needed]} who along with his orchestra, The Divine Hand Ensemble, regularly holds said concerts. It is also used in popular music genres, such as rock.

Plasma Sphere

A plasma sphere, plasma ball, or plasma globeis a clear glass container filled with noble gases, usually a mixture of neon, krypton, and xenon, that has a high-voltage electrode in the center of the container. When voltage is applied, a plasma is formed within the container. Plasma filaments extend from the inner electrode to the outer glass insulator, giving the appearance of multiple constant beams of colored light. Plasma balls were popular as novelty items in the 1980s.

Plasma sphere in daylight

Plasma sphere set in black box with CFL bulb.  The sphere (already plugged in) is creating a current in the bulb making it glow.

Professor Will Fox and Ben Fox with plasma sphere

Joanna Fox does her magic.

Carlos Romero-Talamás

Marc Swisdak

Brian Beaudoin

Pictures of the activated plasma sphere

Optics(polarization discs, holograms, light polarization)

Milli Ayako, Rushil Dandamudi, and Carlos Romero-Talamás

Sheng-Wei Wang, Milli Ayako, and Rushil Dandamudi

Milli Ayako explains how beautiful color patterns form in transparent objects using light polarization.

Marc Swisdak explains how iron filings show the field from a magnet.   

Sheng-Wei Wang and Sabrina Wang setting up the hologram (shown below).    Diffraction "grating" rainbow discs lie on the front of the table.

Butterfly hologram set up by Meredith Pettit in a very, very dark room on Maryland Day 2024.  The same experiment is used in 2025.

Diffraction "grating" rainbow discs

Diffraction "grating" rainbowglasses and discs

Looking out the window normally.

The same scene using diffraction "grating" rainbow glasses or disc.

People Pictures

Shawn Fickes

Taking a break.

Shelley Wang, Milli Ayako, and Rushil Dandamudi

Acknowledgements

We wish to thank our volunteers who explained the experiments to the many people who attended Maryland Day:   Hannah McCright, IREAP undergrad (Beaudoin); Milli Ayako, IREAP/ECE graduate student (Chembo); Shelley Wang, IREAP/Physics graduate student (Lathrop); Sheng-Wei Wang, IREAP/MSE graduate student (Ocampo); Rushil Dandamudi, Computer Science graduate student; Dr. Marc Swisdak  and Profs.  Brian Beaudoin, Carlos Romero-Talamás and Will Fox.   

We whole-heartedly wish to thank Meredith Pettit, Chair of the IREAP Maryland Day 2025 Committee, for taking the pictures of the experiments and for her untiring efforts to make IREAP's presentations at Maryland Day a huge success. 

Webpage:  Dorothea F. Brosius

Archive: Maryland Day 2024, Maryland Day 2023