black body radiation experiment pdf writer

Under these circumstances, an incident light beam will produce electron-hole pairs in the depletion region and allow an electric current to flow once more. Since almost no free electrical carriers are present there, the current through the diode is effectively reduced to zero. In this case, the positive 'holes' will be attracted to the top and the electrons towards the bottom, leaving a 'depletion layer' in the middle.

If this device is 'reverse-biased' so that the upper electrode is more negative than the lower one, the charge carriers will separate as shown in Figure 2.2. In the upper region of the diode, electric current is transported by positive charge carriers called 'holes' in the lower region, the current carriers are negatively charged electrons. Schematically it looks like the sketch shown in Figure 2.1. A silicon diode is the most elementary semiconductor structure one can construct. They are also responsible for the seasonal variations in average temperature that mark the difference between summer and winter.Ģ.2 Measuring Light Intensity The basic device for measuring light intensity in these experiments is a reverse-biased silicon diode. These effects are a consequence only of geometry, but they are basic to many aspects of physics. To get familiar with the equipment, you will first make some simpler measurements of light intensity as a function of the distance from the source and the angle of the sensor with respect to the beam. You will measure the spectrum of photons produced by a tungsten filament at various temperatures and compare the results with both the classical and quantum mechanical predictions.

In fact, the failure of classical mechanics to provide a finite value for thermal emission of electromagnetic radiation led to the discovery that light was indeed emitted in discrete quanta. Such a system has some unusual properties: the 'particles' are, by definition, relativistic and quantum mechanical effects are significant. Another simple physical system is a photon 'gas' in equilibrium with its surroundings. As a consequence, helium is extremely hard to liquefy – it must be reduced to 4.2 K before it can condense. An 'ideal gas' thermometer works particularly well with helium because the interaction between atoms is very weak. Suggestion: Bring a floppy disk or a USB memory stick to class – it can be used for copying the Excel spreadsheets used for the lab.Ģ.1 Introduction In Experiment 1, we explored the behavior of simple gases such as helium.

Light Intensity, Blackbody Radiation and the StefanBoltzmann Law

Black body radiation experiment pdf writer