This is a rough guide of applicable demonstrations for some upper division physics classes offered at UCSC. These lists are suggestions based off of the progression of the textbooks most recently used for the classes. The textbooks used to make suggestions are listed, and adjustments to proposed demonstrations may be necessary should a different textbook be used.

Physics 102: Modern Physics

Photoelectric Effect This demonstration shows that certain wavelengths of light can push electrons from the surface of photoemissive solids by showing a charged plate lose charge when lit with a UV light.

Photocell This demonstrates a physical application to the photoelectric effect. When photons bombard a photoemissive material a small current is induced. This current can power a small lightbulb or other electronics. The actual mechanism of creating a current changes for different types of photocells (photoconductive vs. photoemissive vs. photovoltaic cells)

Maltese Cross A fluorescent screen is illuminated by a beam of electrons. A Maltese cross is put in the path of the electron beam and a shadow is produced on the fluorescent screen, showing the particle nature of electrons. A bar magnet can be used to show distortions in the path of an electron beam as it will distort the image created on the screen.

Electron Diffraction Apparatus This is a demonstration of electrons acting as a wave. The fluorescent screen shows interference patterns of an electron beam shone through a sheet of graphite, which acts as a grating.

Thermoelectric Converter, Thermocouple This demonstration shows that a change in temperature of two conducting materials can create a potential difference that causes a current to flow.

Fluorescent Materials This demonstration shows that when exposed to high-energy light (UV), electrons in fluorescent materials can jump to higher energy levels and then fall back down. In this process there are photons released by the electrons cascading down that cause the material to emit light in the visible spectrum (even though the light source used to “charge” the electrons is not itself in the visible range).

Superconductivity This demonstration shows the Meisner Effect: superconductors expel all magnetic flux from within their volume. The result of this is that a permanent magnet will float above the superconducting material as long as it stays cold enough.

Physics 105: Mechanics

Double Pendulum The double pendulum connected by a spring (also called coupled pendulum) is a demonstration with complex modes and movement that can be modeled with the Lagrangian. Seeing the different modes in action is a great way to relate the physical to the math.

Atwood and Double Atwood Machines: Both the single and double Atwood machines (like the coupled pendulum) are good demonstrations to use when discussing the Lagrangian.

Motor-driven Gyroscope This demonstration is a good one to present during the lesson on rotational motion for rigid bodies. By adding and subtracting weight from the gyroscope you can see how the precession of the gyroscope will change.

Gyroscope to Measure Precession and Nutation This gyroscope demonstration shows both precession and the different nutation patterns that occur when the gyroscope is pushed off balance.

Physics 107: Fluid Dynamics

Heron’s Fountain This new demonstration shows the principles of pneumatics and hydraulics by creating a fountain through pressure differences in several closed containers.

Viscosity and Stoke’s Equation In this demonstration two tubes (one filled with water and the other with glycerin) show how viscosity affects the velocity of a sinking object. Using the measured velocity and applying Stoke’s equation we can find the viscosity of the fluid through which the object is sinking.

Glycerin Machine This demonstration shows laminar flow and can be used in discussions of reverse entropy. The glycerin machine can also be used as an analogy to implicate order in quantum theory and the nuclear “spin echo” that plays an important role in Magnetic Resonance Imaging technologies.

Physics 110 A & B: Electricity, Magnetism, and Optics

Electric Field Apparatus This demonstration shows how electric field lines curve from one charged point to another. You can see the field lines between two point charges, between two concentric rings, and from two parallel plates.

Electric Fields Inside a Sphere This demo shows students definitively that there is no electric field or charge inside of a charged sphere, showing Gauss’ law to be true. Some students may find it hard to believe that there should not be a field inside a sphere, and this demonstration can serve to convince them of this fact.

Electrostatic Pendulum This demonstration shows charging by induction of a pendulum which causes it to oscillate. The pendulum is metal and placed next to a Van der Graaf generator that induces a positive charge on one side of the sphere. This positive charge is attracted to the generator and swings closer to the generator. At some point the force of gravity on the sphere will overcome the attractive force between the sphere and the generator and the sphere will swing back. This process continues as the pendulum gets closer and closer to the generator.

Thermoelectric Converter; Thermocouple This demonstration shows that a change in temperature of two conducting materials can create a potential difference that causes a current to flow.

Helmholtz Coil This demonstration can be used to show how charged particles (in this case, an electron beam) with an initial velocity move in a spiral in the direction of the magnetic field.

Eddy Current Pendulum The eddy current pendulum is a great demonstration to show how eddy currents affect the path of motion of two pendulums. In the solid aluminum pendulum, eddy currents are created in the bulk of the material due to the relative motion of the pendulum with respect to the stationary magnet. This leads to the pendulum quickly losing momentum, seemingly on its own accord. The pendulum with small slits in it does not stop when swinging through a magnetic field because the small slits discourage eddy currents from forming.

Faraday’s Laws This demo shows Faraday’s Law, a basic principle of electrmagnetism predicting how an electromotive force can be generated by passing a bar magnet through a loop of wire. The result of this is a pulse of current that travels through the circuit. This pulse can be shown either using an oscilloscope, which will show the pulse in voltage, or using a simple ammeter that shows the real time voltage passing through the loop.

Lamp in Series with Inductance (Lenz’s Law) This demo shows Lenz’s law, which states that when a current is induced in a conductor due to Faraday’s law, its direction will be such that the magnetic field it produces will oppose the change that produced it. In this demo, we show that you can slow a current moving through a wire by putting a solenoid in series with a lightbulb. The induced current due to the changing magnetic field will oppose the current created by the power supply, the result of which is that the lightbulb in series with an inductor will light more slowly than one without an inductor.

Wonder Tubes (Lenz’s Law) This demonstrates Lenz’s Law by showing a magnetic cylinder falling more slowly through an aluminum tube than an aluminum cylinder. The eddy currents created in the aluminum tube by the falling magnet induce a magnetic field that causes a force to oppose gravitational force pulling the magnet downward.

Jumping Ring (Lenz’s Law) This demo shows Lenz’s law by showing a solid aluminum ring “jumping” off of a solenoid fitted with an iron core. However, when a slit is cut in the ring it does not jump off. This is because the slit in the aluminum ring discourages the formation of the eddy currents that create a magnetic field to oppose the change in magnetic field due to the solenoid.

Induction Coils This demo shows the properties of induction by connecting an inductor in parallel with a lightbulb and switch. The lightbulb is first illuminated when there is no iron core in the solenoid. While the lightbulb remains lit, the iron core is placed in the solenoid. Now, when the lightbulb is turned off, it will briefly become much brighter than it was before extinguishing entirely.

Light Pipe This demonstration shows how the angle of incidence of a laser on a plexiglass light guide can change how the light is reflected and refracted along the guide. You can show a variety of scenarios from total internal reflection to total transmission and accompanying refraction through the guide.

Physics 112: Thermodynamics and Statistical Mechanics

Stirling Engine The Stirling engine is an example of a heat engine that converts heat into mechanical motion. It does through the cycling compression and expansion of gas in the two cylinders. One cylinder is heated with a flame and the other is cooled by a heat sink. The cool cylinder will contract as heat is transferred to the heat sink and the air will fill the heated cylinder. The gas will expand and will once again fill the cool cylinder.

Hero’s Engine This is another demonstration of how to convert thermal energy into mechanical. A special glass container filled with water is placed over a bunsen burner. Two glass tubes coming out of the sides of the container direct the steam coming out of the container in such a way as to spin the container on its axis.

Triple Point of Water This demonstration shows the triple point of water using a large vacuum chamber and a small dish of cold water. Requires 10-15 minute prep prior to demonstration and presence of current Demo Room manager or other qualified staff member.

Curie Point of Iron This demonstration shows that at its Curie temperature (achieved by using a blowtorch), a chunk of iron will lose its magnetic properties. Conversely, as it cools it will re-magnetize.