Advanced Laboratory: Phys39 / Phys169

Oral presentations: Wednesday November 15.

Zoom: https://brandeis.zoom.us/my/sethfraden

Sign up for a time slot.

 

Guidelines for oral presentations for advanced lab.

 

Each team will give an oral presentation of their project.

 

I recommend using Powerpoint. You have 20 minutes maximum. This is a strict limit; rehearse your presentation in advance. Do it at least once using Zoom. Use a mouse to coordinate your spoken words with the content on your slide. Be able to annotate slides in response to questions. The intended audience of your presentation are your classmates who have not yet taken the lab. Imagine yourself at the beginning of the lab. What would you have appreciated being told before embarking on the lab? One objective of the presentation is to make the lab easier for the students in future versions of this class. In addition to whatever you think is important to include in your presentation, incorporate the following features

 

·  Each slide should make one point; use at least one illustration or graphic per slide. Avoid lists.

·  When describing theory and experiment emphasize intuition and insight. Interpret the results. Explain their meaning.

·  What physics does the lab address? Give the big picture. Be brief.

·  Give some history and context. Be brief.

·  What techniques are used? Describe in some detail.

·  Show actual data, how you processed the data and what the data means. Describe in some detail.

·  What aspects of the lab worked well? Which didn’t?

·  How general is the phenomena you studied? What are other examples in physics, in science where the phenomena you studied also applies?

·  Give advice. Suggest improvements.

 

Specific suggestions for the first oral presentations on control.

 

Some suggestions of specific content to include in the control presentation. You don’t need to include all of these and you can add your own content as well.

·       A theoretical model of a TEC plus thermistor is described in the app “ModelingTECv2.mlapp”. In the model there are two elements; the TEC and the thermistor block. Each of these elements has a thermal mass. Describe how the model idealizes the real case. What is the relationship between the idealized model and the mathematical equations? How does the model treat the relationship between heat and temperature? Compare the performance of the model with your data taken on the TEC.

·       Why is proportional control unstable? Can you make a mathematical model that explains it? Explore how stability is related to thermal mass and gain with the app “ModelingTECv2.mlapp”. Can you explain what you observe and compare with experiment.

·       Describe the hardware and software. What is the function of each component?

·       Describe manual, proportional and proportional / integral control. Compare the performance of the model and your experiments.

·       What are examples of control applications besides temperature?

·       Why is there droop in proportional control?

·       How does integral control eliminate droop?

·       How would maximize the speed to reach the set temperature with and without overshoot?

·       Describe Ziegler-Nichols tuning. What is the physical basis?

·       What is the physics of a thermistor? Are there other electronic ways to measure temperature? What are their accuracy? Cost? Ease of use?

·       What is the physics of a TEC? How much power is lost in resistive heating? What is a mathematical model of the heat flow through a TEC? How does the heat flow through a TEC impact your experiments? What is the maximum cooling power that can be supplied by a TEC? What would happen to your experiment if the radiator pump and fan stop working?

·       What is an h-bridge and how does it work? What are other uses of an h-bridge?

 

 

Guidelines for written lab report:

Each student will write a lab report. There are examples from previous students on the website. Roughly it should be about 10 pages long, and address the same points described above in the oral guidelines section.

 

Specific suggestions for the second oral presentation on the Angstrom experiment.

Oral presentations: Wednesday December 6.

Sign up for a time slot.

 

Some suggestions of specific content to include in the control presentation. You don’t need to include all of these and you can add your own content as well.

 

 

·       What is the Biot number? What is its significance?

·       How does the decay of temperature along a rod heated at one end and cooled along its perimeter vary as a function of radius?

 

·       One can obtain measurements of the thermal conductivity and heat loss of the metal rod by applying a constant temperature at the bottom of a rod and measuring the temperature along the rod as a function of position. What are the advantages of using the time varying Angstrom method compared to the constant temperature case?

·       What range of frequencies can you apply in your setup and get useful data? What happens in the limits of  and ? What is a large frequency in this case and what is a small frequency? Large and small compared to what?

·       How does the amplitude of a time varying temperature change as a function of distance and frequency? What are the implications of this for your experiment?

·       Does the numerical value of heat loss coefficient that you measure make sense?

·       Does the numerical value of the thermal conductivity coefficient that you measure make sense?

 

·       What are the solutions for the temperature profile along an infinite and along a finite rod of length L that has a constant temperature (higher than room temperature) at the bottom and cools to the room from the side? For example, if the bottom temperature was held constant at 60C and the room was constant at 20C.

·       Which model fits your data better?

·       Does the Angstrom theory assume an infinitely long rod? Does the finite length of the rod lead to systematic errors in the analysis of your experiments?

 

·       What did you learn in this class? Did ChatGPT help or hinder? Have you worked with Matlab before? Was Matlab useful? Have you worked with GUI’s? Did you find them useful? Have you worked with Arduinos before? What did you learn about them? Have you solved Laplace’s equation for diffusion of concentration or heat or voltage before? What did you learn about solutions of the diffusion equation? Can you explain the difference between heat and temperature? Can you describe how heat is transported and how temperature waves are propagated?