Experiments for the VOAF Course

2. String vibrations and travelling waves

Transverse standing waves on a string

Demonstration of individual modes excited on a string with fixed ends.

Longitudinal standing waves on a spring

Demonstration of modes of longitudinal standing waves excited on a spring using a vibration generator.

3. Dispersion relation, wave packets, group velocity

Fourier transform of a sound signal

Demonstration of the time evolution of a sound signal recorded by a microphone and its corresponding frequency spectrum.

Spectrometer as an example of a Fourier transform

The spectrometer performs a Fourier transform of incoming light and displays its (frequency) spectrum as a function of wavelength.

Group velocity on water

Demonstration of group velocity for waves on water.

4. Wave reflections

Wave reflections demonstrated on a torsion wave machine (YouTube)

Demonstration of wave reflection at the end (termination) of a torsion wave machine.

Demonstration of wave transmission and reflection at the junction of two torsion wave machines.

Reflection of voltage waves on telegraph line

Demonstration of voltage wave propagation along a telegraph line and their reflection at free and fixed ends.

5. Waves in space

Interference of plane waves

Using a Fresnel mirror, we let two plane waves with a small angle between their propagation directions interfere on a screen.

6. Electromagnetic waves

Demonstration of a waveguide for a microwave source

First, microwaves are guided almost without loss through a flexible waveguide. The second part demonstrates the existence of a minimal waveguide size below which waves cannot propagate.

7. Polarization

Microwave polarization and polarizing filter

Demonstration of the passage of linearly polarized microwaves through a linear polarizer.

Light polarization and Malus's law

Demonstration of Malus's law – change in intensity of linearly polarized light passing through a linear polarizer depending on the orientation of the polarizer's transmission axis.

Polarization and the principle of an LCD display

A modified LCD display lacks the top polarizing film. Because of this, no image is visible—only a white surface. By applying a suitably oriented linear polarizer, the image can be made visible.

Birefringence in Iceland spar

Iceland spar (calcite) is a material exhibiting birefringence. Due to this phenomenon, light rays with mutually perpendicular polarizations are refracted at different angles. On the screen, we can therefore observe two images of the halogen lamp, each formed by linearly polarized light with perpendicular polarization.

Half-wave and quarter-wave plates

Wave plates cause a phase shift between two perpendicular polarizations. We demonstrate the effect of a quarter-wave and half-wave plate on linearly polarized light.

Optical activity of a sugar solution

We demonstrate the rotation of the plane of linearly polarized light after passing through a sugar solution in monochromatic and white light.

Law of reflection, Snell’s law of refraction, total internal reflection

On an optical disk with a semicircular lens, we demonstrate the law of reflection, Snell’s law of refraction, and the phenomenon of total internal reflection.

Polarization by reflection, Brewster’s angle

Light is partially linearly polarized upon reflection. If the angle of incidence equals Brewster’s angle (which is defined by the reflected and transmitted rays forming a right angle), the reflected light is linearly polarized with the polarization direction perpendicular to the plane of incidence.

8. Interference and diffraction

Michelson interferometer

The Michelson interferometer as an example of interference of two beams depending on their path difference.

Coherence length and interference visibility

Michelson interferometer with adjustable path length of one of the beams to measure the coherence length of a given light source.

Diffraction pattern from complementary apertures

Diffraction patterns from complementary apertures are identical outside the area of incident light according to Babinet’s principle.

Fraunhofer diffraction

Demonstration of Fraunhofer diffraction on various apertures in a screen: slit, double slit, diffraction grating, circular aperture.

Dispersion of white light on a diffraction grating

Demonstration of the dispersion of light with a continuous spectrum on a diffraction grating.

Effect of source extension on diffraction pattern visibility

A non-point light source emitting spatially incoherent waves affects the visibility (blurriness) of the diffraction pattern.

10. Limits of classical physics

Balmer series of hydrogen

The Balmer lamp emits light produced by excitation of hydrogen atoms. Using a spectrometer, we display the spectrum primarily in the visible region and compare it with the prediction of the Rydberg formula.