Modern Physics

Detection of radioactive radiation with the Wilson cloudchamber

Absorption spectra

Principle

Electron shells of metal atoms in the gas phase can be elevated to an excited state by light. If light is passed through the metal vapour, various lines will be absent from its spectrum afterwards. These lines correspond to the energy levels of those electrons in th ...

Model ESR experiment

Visualisation of radioactive radiation with a cloud chamberwith Peltier cooling

The deflection of beta radiation in a magnetic field

Level control

Principle

The stream of particles emitted from a radioactive source diminishes over time. A radioactive substance decays according to certain physical laws. In the special case of a radioactive substance comprising only one irradiating component, the quantity of mater ...

Quantum eraser

Principle

A Mach-Zehnder interferometer is lit by a diverged laser beam. Ring-shaped interference patterns then appear on the screen behind the interferometer. If polarisation filters with perpendicular alignments are placed in the two arms of the interferometer, the interfer ...

Diffraction at a slit and Heisenberg's uncertainty principle

Principle

The distribution of intensity in the Fraunhofer diffraction pattern of a slit is measured. The results are evaluated both from the wave pattern view point, by comparison with Kirchhoff's diffraction formula, and from the quantum mechanics standpoint to confirm Heise ...

Elementary charge and Millikan experiment

Principle

Charged oil droplets subjected to an electric field and to gravity between the plates of a capacitor are accelerated by application of a voltage. The elementary charge is determined from the velocities in the direction of gravity and in the opposite direction.

Specific charge of the electron e/m

Principle

Electrons are accelerated in an electric field and enter a magnetic field at right angles to the direction of motion. The specific charge of the electron is determined from the accelerating voltage, the magnetic field strength and the radius of the electron orbit.

Franck-Hertz experiment with a Hg tube

Principle

Electrons are accelerated in a tube filled with mercury vapour. The excitation energy of mercury is determined from the distance between the equidistant minima of the electron current in a variable opposing electric field.

Tasks

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Franck-Hertz experiment with a Ne tube

Principle

Electrons are accelerated in a tube filled with neon vapour. The excitation energy of neon is determined from the distance between the equidistant minima of the electron current in a variable opposing electric field.

Tasks

1. ...

Planck's "quantum of action" and photoelectric effect (line separation by interference filters)

Principle:

A photo-cell is illuminated with light of different wavel lengths. Planck's quantum of action or Planck's constant (h), is determined from the photoelectric voltages measured.

Tasks:

1. To determine Planck's quantum of action from the pho ...

Planck's "quantum of action" and extern photoelectric effec effect (line separation by a diffraction grating)

Principle

The photoelectric effect is one key experiment in the development of modern physics. White light from a filament lamp is filtered by a grating spectrometer and illuminates a photocell. The maximum energy of the ejected electrons depends only on the frequency of the ...