2010-PHYS-339 Project
From McGill University Physics Department Technical Services Wiki
The project section of PHYS-339 Measurements Lab is the final big pay off. For the last 3 to 4 weeks (depending on the calendar and political winds) the students are able to apply the techniques they have learned to a project of their choosing. While there are some experiments which are listed for students who lack the enthusiasm to propose their own project, students are strongly encouraged to find something which fits the requirements and capabilities of the course and in which the students are personally interested.
Introduction
As mentioned in the course description, the last four weeks of this course form a project experiment which you select from the attached list or devise yourself. In either case you will retain complete control over the techniques and objectives of the experiment as we will not be preparing the handout/guide -- you will.
When you have selected a project, you should do some background reading a prepare a proposal. We will be happy to discuss the project and proposal at any time after you have done some preparation and have some concrete suggestions of your own. By the submission deadline you should have a fair idea of what you can do in four weeks so keep your expectations realistic.
The proposal should outline the physics involved in the experiment and contain a detailed list of objectives and expected results. There should also be a discussion of any analysis procedures you expect to use. It should serve as a guide both to you, when conducting the experiment, and to us. when grading the report. A key part of the proposal is the agenda: a description of what you expect to get done each week -- this will serve to keep you on track and allow us to monitor your progress. Finally it should contain a list of references you have consulted during the preparation of the proposal and expect to use while you are carrying out the work. The proposal must not exceed four pages in length.
Projects
Measuring the efficiency of a Stirling Engine (Atchia & Egan-Pimbett)
The mechanical properties of a Stirling engine are measured. These are used to determine the power output of the Stirling engine extracting work from several different temperature gradients. We found the engine's frequency depends linearly on the temperature difference while the engine's power goes as temperature cubed.
Study of Human Vocal Formants (Caroll & Quirt)
This investigation considers the relevancy of windowing when analyzing formant frequencies, evaluates the difference between the sexes' vowel sound formants, and compares appropriateness of the Rode© NT5 microphone to the Audio Technica© ATM41a for vocal analysis.
Windowing was found to have no effect on the clarity of vowel sound formants due to high sampling rate. It was found, as expected, that male vowel sound formant frequencies were consistently lower than those of the female. Lastly, the frequency response of the Rode© microphone was found to better than the Audio Technica© thereby making it better suited for vocal analysis.
- Full Document (PDF) (http://www.ugrad.physics.mcgill.ca/Library/339-2010-Vocal_Formants.pdf)
Franck-Hertz Experiment (Heslop, Thibau & Thomas)
We investigate the character of energy states in mercury atoms by accelerating electrons through mercury vapour in a heated vacuum tube. Electrons are ejected from a cathode through the vapour, and those reaching an anode are measured as a current. Periodic dips in this current as a function of an applied accelerating potential suggest the quantization of atomic energy states. Measurements are taken at different temperatures, and the different results are discussed.
Properties of Transistors (Beausoleil & Xing)
Transistors are commonly used semiconductor devices. Understanding the properties of transistors is crucial for understanding modern electronics. In this experiment, we constructed the charateristic curves for bipolar junction transistor and field effect transistors. The temperature dependence of the junction field effect transistors is also studied. We found that the saturated drain current changes by -19.7 ± 0.2 μA / °C as temperature increases.
- Full Document (http://www.ugrad.physics.mcgill.ca/Library/339-2010-Properties_of_Transistors.pdf)
Magnetometer (Staiger & Tremblay-Sher)
There are many ways to measure magnetic field strength with one way using the change in magnetic flux to induce an electromotive force. This type of magnetometer is build and tested near a magnetic source. We were able to show that it is effective as a magnetometer, but it is not very practical.
Full document (http://www.ugrad.physics.mcgill.ca/Library/339-2010-Magnetometer.pdf)
Properties of the Thermocouple (Farookhi & Yarkoni)
This experiment investigates a K-type thermocouple in order to demonstrate the Seebeck and Peltier coefficients. Temperature dependency of voltage and vice-versa are characterized for this thermocouple. A homemade thermocouple is built to find current which is found as 40.1 ± 0.5 mA with junctions in liquid nitrogen and at room temperature, and 196.8 ± 0.6 mA for junctions in liquid nitrogen and being heated by a blow torch.
Full document (http://www.ugrad.physics.mcgill.ca/Library/339-2010-Thermocouples.pdf)
Resistivity Profile of Silicon (Blumenthal & McGillivray)
The temperature-dependent resistivity profile of a silicon semicondutor was determined using a four-point probe technique. The resistivity was analyzed in temperature range from 77K - 367K using liquid nitrogen and a poorly conducting wire for cooling and heating respectively. It was found that the silicon sample was infact doped, causing the resistivity to increase in proportion to temperature (opposite to what is found in intrinsic silicon). We also demonstrate the abolishment of error due to contact resistance by using the four-point probe technique rather than simply two-probe by comparing the I-V traces at room temperature for each.
Resistance of a Thermistor (Ye & Yao)
In this experiment, we determined the characteristic curve of a thermistors resistance with respect to temperature by fitting five sets of highly coherent measurement runs. We were able to maintain a high degree of accuracy in our data by measuring the two variables as directly as possible while avoiding intermediate steps. The approximation to a β-parameter curve clearly failed, as the thermistor was shown to exhibit a behavior closer to that described by the third order approximation of the Steinhart-Hart equation. The thermistor's resistance at room temperature is found to be 4.3(1)kΩ. The best fit curve for the resistivity vs. temperature relationship was found to be 1/T = A + B ln(R) + C ln(R)3 with A = 2.34(2) x 10-3, B = 6.8(7) x 10-6 and C = 162(3) x 10-6. As an extension to this project, we also determined the time constant of the thermistor to be t = 0.135(7)s.
Vortices (Dueck & Gosselin)
We investigate the effect of flowing water past immersed bodies. It produces a pattern in the fluid known as Von Kármán vortex streets that depends upon three parameters: Reynolds, Roshko and Strouhal numbers. We use stratification to isolate the formation of the wakes on a 2-D plane, allowing us to capture movement with a camera. We study the effects of speeds and cylinder diameters on the wake's properties.
Resistance of a Thermistor (Rousseau & Tachjian)
The experiment consisted of measureing the resistance of a thermistor as a function of temperature. This was accomplished by applying a voltage across the thermistor via a custom built current source, whilst the thermistor was at a given temperature. The experiment was conducted for two negative coefficient thermistors. A characteristic value β of 3771.3 ± 0.3 K was found for thermistor A and a β value of 2869.0 ± 0.8 K was calculated for thermistor B. These values were charicterized with certainty for the temperature range of -50°C to +50°C.
Photoelectric Effect (Lima Padilla & Zapalowicz)
We discuss methods experimented with in an attempt to demonstrate the photoelectric effect and determine the work function of certain metals. Ultimately, we were unsuccessful in determining the work function of any metal whatsoever, however we did obtain results that could be interpreted as the photoemission of electrons.
Full document (http://www.ugrad.physics.mcgill.ca/Library/339-2010-Photoelectric_Effect.pdf)
Differential Thermal Analysis (Bodzay & Connor)
We implemented a differential thermal analysis setup to obtain data pertaining to temperature differences between an active sample and a reference sample undergoing the sames heating regimen for a variety of samples. Linear fits were applied to this data to determine points. We determined the boiling point of ethanol to be 78 ± 2°C, the boiling point of methanol to be 60 ± 5°C, the boiling point of water to be 98 ± 5°C, and the boiling point of isopropanol to be 83 ± 3°C.
Available Projects
The following projects are available. Where applicable, equipment limitations are indicated. Remember that none of these experiments provide a guide on how to proceed, this is your responsibility. You may note that Peltier/Seebeck Effect has been removed since last year, this is not an oversight, it was deliberate.
Resonant RLC Circuits
The Labmaster can be configured to trigger ADC conversions upon a TTL edge which can be generated by the i9513 timer/counter; this will allow more precise time control than was evident in the function generator exercise. Both the frequency response and temporal response of various RLC circuits can be measured. This starting point could be extended in a number of possible directions such as a high-precision capacitance / inductance meter or studies of the effect of dielectric/ferromagnetic cored upon inductance.
Capacitance of the P-N Junction
A reverse-biased diode exhibits a capacitance which is a function of the reverse bias. Since the capacitance is of order 50~pF some care needs to be taken in the design of the measurement.
Franck-Hertz Experiment (1 setup)
In 1925 James Franck and Gustav Hertz were awarded a Nobel prize for "their discovery of the laws governing the impact of an electron upon an atom." Their results can be replicated by observing the energy distribution of electrons after being accelerated through mercury vapour. The effect of electrons transferring kinetic energy to mercury atoms by promoting bound electrons into excited states can be observed as periodic fluctuations in the current as a function of the accelerating potential.
Characteristics of Transistors
With some simple additional electronics it is possible to automate the process of generating "handbook" characteristic curves for bipolar and field-effect transistors.
Resistance of a Thermistor
Thermistors are narrow band-gap semiconductors which are used as thermometers due to the great sensitivity of the resistance as a function of temperature.
Optical Polarization
Certain molecules, for example glucose and fructose, have the property that they rotate the polarization of transmitted light. The angle of rotation if a function of wavelength. Using an stepping motors to control both an interferometer and polarizing filters, it would be possible to investigate this phenomena.
Differential Thermal Analysis
DTA is a technique where a a test sample and an inert sample are heated or cooled under identical conditions, while recording the temperature difference between the samples. When a phase change occurs in the sample the absorption or liberation of heat will be observed in the temperature difference between the sample and the reference. Applying the techniques demonstrated in the servo control lab, a DTA system can be implemented.
Projects performed in previous years
- 2006
- 2005 - this part is a bit incomplete, it was supposed to be updated by the students involved ... they lost interest around the time of report submission!
- 2002
- 2000
