HOW TO WRITE LABORATORY REPORTS LABORATORY REPORT FORMAT

The laboratory reports are to be formal. That is, the laboratory report is recorded in such a way that the experiment could be repeated by a reader of the report. LAYOUT Formal reports must be generated by a word processor, they are NOT to be hand written. (MS-OfficeTM is available for use on computers in the Learning Centres). Similarly it is best to use drawing and graphics programs (e.g. MS-Paint, & AutoCAD) for producing images and diagrams.

The report must be laser, or ink-jet, printed on ONE SIDE of A4 sized paper. Colour printing is acceptable, but do NOT make it fancy coloured. Overly artistic reports are NOT professional. Reports are to be stapled in the upper left-hand corner only. Do NOT submit reports in binders, plastic folders, or other fancy coverings. (This just makes it difficult for reading and marking). WORDING

The reports are written in the third person. This means that NO gender or person referencing titles are to be used. That is do NOT use words like: I, me, we, he, students, etc. For example; instead of writing: I measured the result to be, write The result was. Also, instead of: I moved the actuator and the group noticed a glow, write The actuator was moved, and a glow was detected. The report must be in proper English, with proper sentence structure. Also the report will be written in correct Tense (i.e. do not incorrectly use, or mix, Past, Present, and Future tenses). For example, the following has incorrect tense: The load will be added, and the beam was bent. Slang and inappropriate abbreviations are NOT to be used. COVER SHEET A cover sheet is required that consists of:

Name of the University, Name of the School, Subject Name, Subject Code, Exercise Number & Name, and Student Name & Number.

Along with the above, usually a non-plagiarism statement is required. For example the following states the work is by the student alone:

The report presented is the sole work of the author. None of this report is plagiarised (in whole or part) from a fellow student's work, or from any un-referenced outside source.

REPORT SECTIONS: The report should contain the following sections:

AIM:

The original aim or purpose for undertaking the experiment should always be recorded. Usually the experiment aim / aims will given in the laboratory manual. If no aim is stated in the manual, then re-word the name of the exercise as an Aim.

Note: Do NOT alter or re-word any given aim. This could be taken as the student changing, or not performing, the given task.

INTRODUCTION: Depending on the intended audience of the report, the introduction may or may not be necessary. When writing the report for peers of similar educational background, then the introduction may not be necessary. However when the intended readers have little knowledge of the reports subject matter, an introduction is vital. The introduction should explain to the reader (in laymans terms) the relevance of the subject matter (the relevance to the experiment), why it was necessary to undertake the report (or experiment), and what benefit the results will be to them or others. In the process, some background information (or theory) to the subject matter may be required. Note: It is perhaps obvious that the main reason the student is undertaking an experiment is to get the marks for the course. However, this is NOT the reason to discuss in the introduction. Instead the student should be discussing the benefit (such as the educational reason) for undertaking the experiment. For example, assume a laboratory is being undertaken to test the load carrying strengths of different materials. In this case, a benefit from this is to determine the best material to use for load bearing structures, such as the best material to use for bridge or building construction.

APPARATUS: Usually ALL equipment used during the experiment must be listed. This list should include the FULL complete name of the given equipment, along with the equipment identification numbers, (such as serial numbers). This is necessary for any future replication of the experiment. However for some course it may be sufficient to state; Engineering Laboratory Equipment. (or something similar). For example: The following will be INCORRECT

Multimeter, Vernier Calliper.

The following is CORRECT

Fluke DM234 Multimeter, ID 1334566, Matsumoto MD54 Vernier Calliper, ID 846626.

PROCEDURE: The procedure must be recorded within the report. This is not only to aid in replication of the experiment, but it also conveys to the more concerned reader exactly what the following results and calculations relate to within the report. In most cases the procedure will be explicitly given within the laboratory manual. In this case it will be sufficient to state; As per Laboratory Manual.

RESULTS: All data, tables, graphs, and diagrams should be recorded in their entirety within the results section. (That is, replicate ALL results that are recorded in the laboratory manual). The results should be neatly presented and completely understandable.

The results section generally contains as little wording as possible, and all explanations of the results should be within the procedure or discussion section. However the results should be

intelligible on their own, without the need for reading any other section of the report. Thus, ALL results need an initial explaining sentence.

Diagrams, like pictures, can convey more information than paragraphs of words. Thus never try to explain something in words that could be better explained by a diagram. Diagrams shall conform to standard engineering drawing practice. Each diagram must contain a descriptive title, that provides enough detail that makes the diagram understandable, independent of the rest of the report. (Titles such as: Task 3 Part C is not descriptive enough). Where possible, multiple result readings should be tabulated.

ALL results must have units on the measurement (such as: m [meters], kg [kilograms]), and the results should only be given to the accuracy valid from the initial observations. Length = 15.3299547482 (is always WRONG). Length = 15.33m (is correct).

Engineering notation shall be used for all numeric data. That is; do NOT report: Length = 0.00135m. Instead use Engineering Notation and report: Length = 1.35mm. ALL graphs and calculations must be formatted correctly, (See the paragraphs below). Format of Graphs: Graphs must have a name at the top of the graph, and the name must be meaningful. For example; Graph of Time Vs Distance would NOT be acceptable. The name should be more explanatory, such as: Graph of the Time of Fall for objects falling a 2m Distance, for Experiment 1B. This detail is necessary so that the graph is understandable, independent of the rest of the report. Do NOT label graphs as: Graph of X vs Y, or ANY other derivative of the Horizontal and Vertical axis. For example, assume an experiment requires the measurement of the Voltage and Current recorded from a heating light bulb. In this case do NOT label the graph as: Graph of Voltage and Current. That label is NOT descriptive, and says nothing more than what could be determined by looking at the Horizontal and Vertical axis. Instead label the graph as something like: Graph of the Response from a Heating Light Bulb. The Horizontal and Vertical axis must be scaled. That is, have ruled axis with numbered tick marks. Each axis must be named (such as Fall Distance), have the symbol (such as d), and have units (i.e. cm). If you need to determine which recordings go on which axis; then the general rule is:

The Independent Variable (the one that is set, given, or user altered during the experiment) is plotted on the Horizontal Axis, while the Dependant Variable (the one that depends on the independent variable, the unknown, measured or calculated value) is plotted on the Vertical Axis.

Format of Calculations: When recording equations and results of equations, working is not shown. Only the equations, data for the equation, and answer is shown. For these experiments, all calculated results must have a valid estimation of the error in the result. The error estimate can be calculated by the above Peters Error Formulas. An example reported calculation is shown below:

Frequency, HzfFCkR

RCf 50 ,01.0 ,1 ,

21

DISCUSSION: The discussion should give an overview of the final results obtained. In effect each result obtained should be discussed, even if the result was as expected. Avoid discussions that are worded as "first we did this, and then we did that, , and finally we did this". Also, avoid rehashing anything that is already stated in previous sections of the report, (such as the introduction).

A full discussion on any discrepancies between expected and observed results will be required, as well as a discussion on any unusual results. Also discuss any tasks that were not completely solved. Avoid simple statements such as --"it didnt work". Instead discus why did it not work, and how could this be solved.

Any questions asked or implied within the laboratory manual, will be answered in this section. However, do NOT just answer the questions like an exam. Instead a full paragraph on each question would be required, that will include the original question and answer to the question, with clear and logical sentence structure. For example, assume the laboratory manual contained the question: Does the two objects fall in the same time. In this case NEVER just answer this as something like: Yes they both have the same time, or worse, just Yes. Instead effectively state the question and the answer as a complete statement, something like:

It was observed that the first object took 0.25s during the fall, and the second object also fell in 0.25s. Thus it is concluded the two objects fell at the same speed.

CONCLUSION: The conclusion is generally the most important section of the report. Usually the conclusion is the only part of the report that is read by a reader, including the person / persons who commissioned the author to do the report.

A conclusion should be drawn from the results, and the aim of the experiment should be answered. For example; if the aim was to determine the value for gravity, then the value and the associated error should be reported. Any conditions on the value, (such as major errors or inconsistencies), should be stated. Finally, if possible, the result should then be compared to the known standard.

The conclusion could also include, in a brief, any unique skills learned or major problems solved during the experiment.

REFERENCES:

All foreign material and literature sources used within the report should be recorded. Each reference will be required to be in the Harvard Style of Referencing. (Which request the reference to have: the author, the reference title, book name, publisher, date of publication, and page numbers used. See the following web sites for more details on the referencing styles:

http://www.griffith.edu.au/ins/training/content_howtoguides.html

http://www.griffith.edu.au/ins/copyright/content_citation.html

SAMPLE REPORT

GRIFFITH UNIVERSITY - GOLD COAST

GRIFFITH SCHOOL OF ENGINEERING

1503ENG - Physics & Chemistry

LABORATORY REPORT

REPORT NUMBER X

'Amplifier Circuits'

The report presented is the sole work of the author. None of this report is plagiarised (in whole or part) from a

fellow student's work, or from any un-referenced outside source.

Student Name: John Citizen. Student Number: S12345678 Date: August, 2004.

EXPERIMENT X: AMPLIFIER CIRCUITS AIM: To observe features of an operational amplifier circuit, and to use the amplifier with a thermocouple to determine the temperature. INTRODUCTION:

An amplifier is an electronic circuit that measures electrical signals and produces an output electrical signal that is proportional, yet much greater, than the input signal. An operational amplifier is a specific type of amplifier, that is designed primarily to amplify input voltage signals but as well as this has numerous signal processing capabilities. The operational amplifier is a complete electronic amplifier contained in a single integrated circuit (I.C.) package. The most common operational amplifier, (and the operational amplifier used for this experiment), is the LM741, (see diagram below).

8 Pin Dual In Line (DIL) LM741 Operational Amplifier.

A thermocouple is an electrical device used for the measurement of temperature. The thermocouple is known as a transducer, for it transducers (converts) thermal energy to electrical energy. A voltage is produced on the output of the thermocouple, which is proportional to the temperature (hence heat energy), i.e. Vout = k temp. The proportionality constant (k) is a constant, but only if the temperature is much less than the saturation point of the thermocouple. Hence a graph of the output voltage against temperature will be linear, provided the temperature is below saturation. The thermocouple consist of two dissimilar metals fused together, with electrical attachments to the metal components, (see diagram below).

Vout = k temperature

THERMOCOUPLE

A thermocouple wire of Platinum Tantalum will be utilised in this experiment. This type of thermocouple is designed to operate over 0-450C, with 0.5C accuracy, and produce an output of 0.25mV/C (ARI Industries, 2007). Although the thermocouple produces an output electrical signal, this electrical signal is not generally of any immediate use for further display or recording circuits. This is due to the thermocouple output signal being of such low level, that it will not directly power such circuits. Consequently, an amplifier is required to boost the output signal to a level that is able to be displayed or recorded. For the complete thermocouple / amplifier system to be used as a temperature measurement system, the relation between the output electrical voltage and the measured temperature is required. This is known as calibration.

Measurement of temperature is extremely significant for virtually all scientific and engineering applications. There are many devices available for the measurement of temperature (for example; spirit thermometers, bi-metallic strips, and thermocouples). However thermocouples have the distinct advantage, in that the output is an immediate electrical signal. Electrical output enables immediate amplification, signal conditioning, transmission, display, and electronic recording. Many other electrical transducers, (such as strain gauges), may also produce low level output signals. Consequently a similar amplification - calibration process as mentioned in this report would be required. APPARATUS:

15V Power Supply - ASTEC Model BM4101, GU Asset: 045142. Hot plate - Kambrook K series, GU Asset: 025468. Digital Multimeter (DMM) - Escort EDM 162 Auto-Ranging, GU Asset: 085426. Thermocouple wire of Platinum - Tantalum, ARI Industries TM PtTa, Sprit Thermometer, -10 to 110 range, Pyrex Breaker, tap water, and ice. 1k and 100k Resistors (0.25W at 5% tolerance), An LM741 operational amplifier, and 4mm Connection Leads. PROCEDURE: 1. Connect up the circuit shown below:

Hot Plate

Thermocouple

Thermometer

Beaker+Water

1k

100k

Op-Amp

V

-12V

+12V

Gnd

Multimeter

2. Half fill the beaker with water, and add ice to fill the beaker. 3. Measure the initial temperature, Ti, and the initial output voltage, Voi. 4. Switch on the hot plate. 5. Record the temperature of the water (T) and the corresponding output voltage (Vo) when the

temperature is 5 above the initial temperature. Repeat the procedure for every 5 temperature changes, for 15 steps. 6. Plot a graph of Output Voltage, Vo, against the temperature, T.

7. Calculate the slope of the graph, s. Where s =VT

o

8. Remove the thermocouple from the water bath, and leave in the open air for at least five (5) minutes. Record the Output Voltage, Vo, from the room temperature.

9. Use the graph of part 6 to determine the room temperature, Tr, by extrapolating from the previously obtained Room temperature Output Voltage.

RESULTS: 2. Initial water temperature and output voltage: Ti = 3 C, Voi = 43mV. 3. Table of Water Temperature, T, and Thermocouple Output Voltage, Vo, with 5C steps.

TABLE OF VOLTAGES PRODUCED AT VARIOUS TEMPERATURES

T (C) 3 8 13 18 23 28 33 38 43 48 53 58 63 68 73

Vo (mV) 43 58 70 85 99 112 127 138 153 166 181 190 200 207 212 6. Graph of above Output Voltage, Vo, and temperature, T, data values.

GRAPH OF THERMOCOUPLE OUTPUT

0

50

100

150

200

250

0 10 20 30 40 50 60 70 80Temperature - T ( C)

Out

put V

olta

ge -

Vo (m

V)

T

Vo

Room Temperature, Vo

7. Calculation of the slope of the graph, s. From the linear portion of the graph,

Vo 134.5 mV and T = 50 C; s =VT

o

Hence, s = 2.69 mV / C

8. Thermocouple output voltage from room temperature, Vo = 129 mV. 9. Room temperature extrapolated from the above graph, Tr = 34 C. DISCUSSION: The inverting operational amplifier circuit used in this experiment has a specific formula for the voltage gain, (which is A = -100k / 1k). However due to the 5% tolerance of each of the resistors, this calculated gain value would not be accurate. Yet, it is not necessary for this laboratory to know the precise gain of the amplifier. This is due to the calibration process applied to the system. Calibration means that, as long as the circuit components remain the same, the relationship between the input temperature and output voltage is know. From the initial readings of water temperature and output voltage, it is evident that there will be an output voltage level, even when the temperature is at zero degrees Centigrade, (0C). Also shown by the Thermocouple Output graph, the obtained points did produce a straight line for a portion of the graph. The graph then, as expected (see the introduction), became non-linear towards the end of the graph. From the graph it is determined that the linear relationship holds for this particular thermocouple system from temperatures of around 0C to a temperature of approximately 60C. A line of best fit was included on the graph. This line was determined by use of the Microsoft Excel Trendline Function, using only the data points from 3C to 53C. That is, only data points that were in the linear portion of the graph were included. The measurement of room temperature was determined to be 34C, which was extrapolated from the line of best fit, (Note that this voltage level is within the linear portion of the graph). This value was verified by the Glass Thermometer reading of 34C, and hence room temperatures can be measured using this designed temperature transducer. The sensitivity (or slope) of this temperature transducer was determined to be, s = 2.69 mV. Note that the slope was obtained from the graphed straight line, and not the collected graph data points. The collected data points have random fluctuations in their values, due to electrical and thermal noise in the system. The straight line is essentially an averaging of the data, which is assumed to be a more accurate result.

CONCLUSION: Operational amplifiers have been observed to show the following features: A positive and negative voltage source is required, which limits power supply options (such as the use of a battery to power the circuit). The amplifier can be used on a transducer device, to amplify the signal from the transducer. The amplifier can produce a signal that can be displayed by a digital Multimeter. It is shown from this report that the designed thermocouple / amplifier system can be used as a temperature measurement system. However the temperature measurement system is only valid over a certain range, which was determined to be from temperatures of 0C to 60C. The calibration curve of the temperature measurement system was obtained, which allows for direct translation between displayed voltage and measured temperature. REFERENCES:

ARi Industries, Table Of Thermocouple Wire Types, Chicago, Illinois, USA. Web site last updated 2005. Viewed Monday, 5 March 2007.

(Referencing the above is necessary for the External Source ARI Industries, 2007 is referenced in the report)