Laboratory of Classical Physics

Head of the Laboratory:

András Böhönyey assistant professor,

Department of Materials Physics,

Pázmány Péter sétány 1/A. room N. 5.76.

Phone: 372-2888

E-mail: boh kukac ludens.elte.hu

Images of the laboratory: image 1, image 2

Classes

  Monday

  Thuesday

Measurements

1.   Gravitational acceleration (images)

The gravitational acceleration (g) is determined by measuring the period-time of a pendulum. The reversible

pendulum, used in this measurement, is a physical pendulum, which can be oscillated around two axes. The

measurement of g with high accuracy (< 0,1%) can be accomplished by a measurement-series successively

changing the centre of gravity of this pendulum by a movable bob.

2.   Elastic constants (images)

The Young's modulus of a bar supported at two ends and loaded at the centre is determined measuring its

deflection by a dial-gauge. Additionally, the torsion modulus of a metallic wire is determined measuring the

period time of a torsion pendulum. 

3.   Harmonic vibration of rods (images)

The harmonic forced oscillations of a bar clamped at one end are investigated measuring the eigen-frequencies

and the resonance curve of the self oscillation. The eddy current excitation and the piezoelectric detection

permit the high accuracy measurement of the dynamical Young's modulus.

4.   Peltier coolers (images)

The thermal properties of a semi-conducting Peltier cooling element are studied. One can measure the current-

equilibrium temperature relationship, the Peltier coefficient characterising the amount of subtracted heat in

cooling, and the Seebeck-coefficient characterising the potential differences appearing between the ends of the

cooling element. Such simple cooling elements are used in refrigerators and for cooling of computer processors.

5.   Specific heat (images)

Specific heat of metallic samples is measured by electric calorimeter. The time-temperature curves are measured

by computer. The measurements are accomplished by two different methods. In the first method the heated up

sample is dropped into the calorimeter and the development of the mutual temperature is measured. In the second

method the sample and the calorimeter are heated together and we measure the change of temperature, and

compare it with the temperature change of the empty calorimeter.

6.   Phase transition of metals (images)

The melting point of metals is measured and the latent heat is calculated in this practice. The metallic samples

are heated in electric furnace. The linear heating and cooling are controlled by thermocontroller. The changes in

temperature of the furnace and the sample are measured by computer. The evaluation of the measured data is

supported by computer as well.

7.   Magnetic susceptibility (images)

Paramagnetic and diamagnetic susceptibility of rod-like samples are measured by the Gouy method. This methods

needs the high accuracy measurement of the magnetic field. The magnetic field is measured by Hall detector, which

is calibrated by a flux-meter. According to the method, a force acts to the sample placed into an inhomogeneous

magnetic field, and this force is proportional to the susceptibility. Thus, measuring the magnetic field and the force,

the susceptibility can be calculated. The force is measured by balance with high accuracy.

8.   Optical microscope, Newton rings

      Refractive index of liquids (images)

The basic principles of the optical microscope are studied in this practice. The main parameters of the

microscope are measured: magnification, focal length and numeric aperture. Using the measured parameters the

resolution can be calculated. The radius of  curvature of a lens is determined by the measurement of the diameter

of Newton rings. Refractive indices of solution serious is measured by Abbe refractometer as a function of the

solution concentration and this enables us to determine the concentration of an unknown solution.

9.   Wave length of light and dispersion of the refractive index (images)

The dispersion properties of grating and prism is investigated using optical goniometer. The light of a spectral lamp

is resolved by a grating and the wavelengths of the spectral lines are determined. Using the wavelength data the

refractive index-wavelength dependence of the prism's glass material is investigated.

10. Fraunhofer and Fresnel diffraction (images)

The diffraction of a laser beam on a slit, double slit, thin string and on a half field is examined using a He-Ne laser.

The Fraunhofer and Fresnel diffraction spectra are measured using a semiconductor detector moved by a step motor.

The detector signal is proportional to the diffracted light intensity. This is measured and evaluated by a computer

program. In the evaluation the size and the arrangement of the diffraction objects can be deduced. The principle is

analogous to the method used in X-ray and electron diffraction to determine the geometrical parameters of a crystal.