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Station 7: University experiments

The nerve cell with Cobra4 Xpert-Link


Interactive learning and teaching system with one neurosimulator for experiments about the nerve cell. Comparison between low and high threshold and stimulus levels, membrane time constant and low pass filtering, excitatory synapse, depolarisation, temporal summation, spatial summation, synaptic amplification by terminal branches, effect of decreasing stimulus, Hebbian synapse, synaptic learning and forgetting, inhibitory synapse, hyperpolarization, spacial inhibitory-excitatory summation, veto synapse.


Equation of state for ideal gases with Cobra4 (gas laws: Gay-Lussac, Amontons, Boyle)


The state of a gas is determined by temperature, pressure and amount of substance. For the limiting case of ideal gases, these state variables are linked via the general equation of state. For a change of state under isochoric conditions this equation becomes Amontons‘ law. In this experiment it is investigated whether Amontons‘ law is valid for a constant amount of gas (air).

Determination of the heat of formation of water


Standard molar enthalpies of formation ΔBHΦ are important compiled thermodynamics tabulation quantities for calculating standard enthalpies of reaction for any arbitrary reaction. They are defined as the heat of reaction occurring in the direct formation of one mole of the pertinent pure substance from the stable pure elements at constant pressure. For spontaneous and quantitative formation reactions, e.g. the conversion of hydrogen and oxygen to water, standard enthalpies of formation can be measured directly using calorimetry.

Stirling engine with Cobra4 Xpert-Link


The Stirling engine is submitted to a load by means of an adjustable torquemeter, or by a coupled generator. Rotation frequency and temperature changes of the Stirling engine are observed. Effective mechanical energy and power, as well as effective electrical power, are assessed as a function of rotation frequency. The amount of energy converted to work per cycle can be determined with the assistance of the pV diagram. The efficiency of the Stirling engine can be estimated.

Charging curve of a capacitor and switch-on behaviour of an inductance with Cobra4 Xpert-Link


A capacitor is charged by way of a resistor. The current is measured as a function of time and the effects of capacitance, resistance and the voltage applied are determined.

Rectification – the number of theoretical trays in a distillation column


The separation power of a rectification (fractionating) column can be determined using an appropriate binary mixture whose equilibrium composition is measured in the distillation flask and in the domed glass head of the distillation apparatus. The number of theoretical trays can be numerically or graphically obtained from the measured values.