VDO

Principle

A set of circular water waves is generated simultaneously and the resulting interference is observed. By increasing the number of interfering circular waves, Huygens’ Principle can be verified. With the aid of plane water waves, diffraction phenomena of waves at different obstacles (slit, edge, double-slit etc.) are investigated. In a further experiment, the principle of “phased array antennas” can be demonstrated. To do so, two circular waves are generated to interfere and the resulting interference pattern on varying the phase of one of the circular waves with respect to the other one is observed.

Tasks

1. Use the comb to generate two circular waves and observe the resulting interference. Increase the number of interfering circular waves up to ten by using all teeth of the comb to demonstrate Huygens’ Principle.
2. Generate plane water waves and use a barrier to demonstrate diffraction at an edge. Then, form a slit and observe diffraction behind the slit. Repeat this experiment for a double-slit.
3. By using the integrated wave generator as well as the external wave generator, generate two circular waves and observe the interference. Vary the phase of the external wave generator and observe the resulting interference pattern to understand the principle of “phased array antennas”.

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.

Tasks

1. Determination of the specific charge of the electron (e/m0) from the path of an electron beam in crossed electric and magnetic fields of variable strength.

Principle

The resistivity and Hall voltage of 2  rectangular germanium samples ( n- and p-) are measured as a function of temperature and magnetic field.

The band spacing, the specific conductivity, the type of charge carrier and the mobility of the charge carriers are determined from the measurements.

Tasks

1. The Hall voltage is measured at room temperature and constant magnetic field as a function of the control current and plotted on a graph (measurement without compensation for defect voltage).
2. The voltage across the sample is measured at room temperature and constant control current as a function of the magnetic induction B.
3. The voltage across the sample is measured at constant control current as a function of the temperature. The band spacing of germanium is calculated from the measurements.
4. The Hall voltage UH is measured as a function of the magnetic induction B, at room temperature. The sign of the charge carriers and the Hall constant RH together with the Hall mobility mH and the carrier concentration p are calculated from the measurements.
5. The Hall voltage UH is measured as a function of temperature at constant magnetic induction B and the values are plotted on a graph.

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. To record the counter current strength I in a Franck-Hertz tube as a function of the anode voltage U.
2. To determine the excitation energy E from the positions of the current strength minima or maxima by difference formation.

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

1. To record the countercurrent strength Ι in a Franck-Hertz tube as a function of the anode voltage U.
2. To determine the excitation energy E from the positions of the current strength minima or maxima by difference formation.