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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

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Eke Reply
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Missy Reply
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Lale Reply
no can't
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Maira Reply
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
Application of nanotechnology in medicine
has a lot of application modern world
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Jyoti Reply
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Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
yes that's correct
I think
Nasa has use it in the 60's, copper as water purification in the moon travel.
nanocopper obvius
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
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Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
analytical skills graphene is prepared to kill any type viruses .
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
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Smarajit Reply
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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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