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Part 4: additional tests

Once you have performed all of the tests outlined above, consider the following tests:

•Transfer the thermocouple from ice water to room temperature air.

How does the time constant compare with the one obtained from the air-to-ice-water transition? Is it different?Why or why not?

•When calculating the time constant for the thermocouple in transition from air to ice water, you measured thetime to go 63.2 percent of the way from the initial temperature (around 21 C) to the final temperature (around 0 C). Using the samegraph, recalculate the time constant using14 C as the starting temperature (i.e., what is the time required to go 63.2 percent ofthe way from 14 C to 0 C?). Is this time constant value significantly different from the initial value you computed? Why orwhy not?

Part 5: thought questions

Document your response to these questions in your lab book.

1. How do the time constants of the thermometer, thermocouple, and thermistor compare? Why is thethermometer“slow”compared to the other devices?

2. How do the time constants obtained for air and water compare? Are they significantly different? If so, explainwhy.

3. Does the instrument need to be at steady state before transferring it to the final medium?

4. How accurate (qualitatively) is the first-order model approximation for the different sensors andmedia?

Part 6: frequency response

From the measured time responses of the thermometer, the thermocouple, and the thermistor, it can be seenthat the response time of these sensors is not instantaneous. From this we can infer that these measurement systems may have somedifficulty following inputs that change quickly. Frequency response is a means of characterizing the dynamic response capabilities of asystem.

The frequency response of a system can be determined by calculating the response of a system to sinusoidalinputs at different frequencies. Two important characteristics are:

  • the magnitude ratio between the output and input waveforms
  • the phase difference between the output and input waveforms

For a first-order system, we can create the frequency response plot using only our knowledge of the system timeconstant. The magnitude ratio can be calculated from the following expression.

equation (4)

The phase difference is determined from expression 5.

equation (5)

In Excel, create a frequency response plot for the thermometer, thermocouple, and thermistor using the timeconstant from the ice water tests. Plot the magnitude ratio on a log-log scale and the phase difference on a semilog scale (logscale of frequency axis). Consider frequencies from 0.1 rad/s to 1000 rad/s. Your plots will look nice if you use ten points perdecade of frequency (i.e., 0.1, 0.2, 0.3,…,1, 2, 3,…, 10, 20, 30,…). Overlay the three magnitude responses on one plot and the three phase responses on another. How do the frequency responsecharacteristics of the thermometer, thermocouple, and thermistor compare?

Part 7: dynamic temperature measurement problem

Include the analysis for this problem in your lab book.

Assume that the thermocouple you used is placed in a water stream at a point where the temperature variessinusoidally between 60 C and 80 C at a frequency of 40 rad/s. Assuming that the thermocouple time constant is the same as thevalue you determined in the ice water case, what will be the range of sinusoidal variation in the temperature readings? Repeat thecalculations for a temperature frequency of 2 rad/s. Now assume the thermocouple is in air instead of water. Determine the range of thevariation using input frequencies of 10 rad/s and 1 rad/s.

Clean up:

Please straighten up your lab work area. Turn off the data acquisition hardware and leave your work area clean.Your help in keeping the lab neat is appreciated.


For this lab, you are to write up the Method section of a full formal report. Guidelines are given in theexample report in the Undergraduate Guide. Avoid presenting results in the Methods section. Your writing assignment is relativelyshort. Take the time to do a good job. Since you will not be submitting Results or Discussion of Results in the report, you willneed to document your results in your lab book. Also, be sure to answer the questions from the lab handout in your lab book.

Questions & Answers

What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
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Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
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Akash Reply
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s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
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Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
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what is biological synthesis of nanoparticles
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what's the easiest and fastest way to the synthesize AgNP?
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Source:  OpenStax, Introduction to mechanical measurements. OpenStax CNX. Oct 18, 2006 Download for free at http://cnx.org/content/col10385/1.1
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