Propotionality, Superpostion and Thevenin equivalent
Labs play a vital role in the engineering curriculum. The hands-on experience of the laboratory goes far beyond simple verification of textbook theory. For most individuals, the laboratory is where the theory becomes less mysterious and things learned in the classroom really start to make sense.
There is another important aspect of the laboratory experience, often unappreciated but equally important. That is the lab write-up. An often-asked question is, “If I understand the theory and can successfully build and test the circuits, why do I need to spend the time to write it up?” Consider this fact of life — Virtually all of the work you do throughout your career will be judged by what you write. An engineer must be able to express ideas on paper clearly enough for others to use and understand. A research scientist who cannot write technical articles that can be understood by peers will never be given credit for what might otherwise be brilliant work. Decisions of extreme importance to your own career such as job offers, promotions and pay raises will almost certainly not be made in your presence. Your written work is likely to be the only personal representation you will have.
It should be obvious by this point that the ability to communicate technical material is an essential skill in engineering. The purpose of the lab write-ups is to develop writing skills that will benefit you throughout your career. You should also find that you are really writing these labs for yourself as they contain material that you may need to refer back to at some point in the future. If you cannot follow your own work six months later, you could experience a rude awakening.
The following guidelines will be used in all of the EE laboratories. The format is by no means universal, but it does contain many common features found in all technical literature. Remember, a reader should be able to know what you are trying to accomplish, how you tried to accomplish it, whether you accomplished it or not, and what went right or wrong.
Title Page: This may be done in such a manner as to help separate labs in a file cabinet later, but it should contain the following information:
• Experiment number and title
• Your name, partner’s name(s)
• Course and section number
• Date the work was completed
Objective: Every experiment has a clear purpose. It should be summarized here. If the lab requires circuit design, the specifications should be listed. If the lab involves measurement and /or verification of theory, the types of measurements to be made should be summarized. The objective section should be short and complete, usually only one paragraph, and should not contain any diagrams or explanations.
Preliminary: All labs require some form of preparation. In some cases, there are problems and questions given in the lab notebook. In others, circuits may need to be designed or component values calculated. In any case, all background work that can be done prior to the lab should be completed. Computer simulations can be a great benefit, allowing an experiment to be modeled before any unnecessary effort is spent in creating the physical system. All of this material, usually condensed to a readable form, should be included in this section.
Analysis: This is generally the part of the lab requiring the most thought. Observations should be compared with expectations or preliminary calculations and any deviations explained. It is not often that things will come out exactly as you think they will. However, there is an explanation for everything. This is where you should convey your understanding of what actually happened. Graph data where appropriate, calculate errors and answer any questions in the manual about the lab observations. Be thorough.
Conclusions: It is usually appropriate to include a few comments that tie your efforts together. These may pertain to the relative success or difficulty of the lab. They may point out a part of the lab that was particularly enlightening to you. Or, looking back on the lab, there may be a few things that you would do differently if you were doing it again from the start. It should also include what you learned from the lab, not so much from a theory standpoint as from the practical side: what worked, what went wrong, and what mistakes you make.
Questions: Answer any questions which might be asked. Start by repeating or paraphrasing the question, then give the answer.
Data: Measurements and observations made in the lab are presented here. Be sure that any data you record is clearly referenced to the circuit from which it came. Use tables and figures properly (see notes on tables and figures in “General Guidelines to a Successful Report”). Avoid reference to step numbers or page numbers in the lab manual. Be sure your data is complete enough for later graphing and analysis. For logic Lab, there will not be much data collection, but this will become very important in other labs. NOTE: The sections listed above are bunched together. In the report, provide only a bullet list of the data that follows. Include page numbers. The data itself is attached after the last page of the rest of the report.
Guidelines for a Good Report
The following are a few things to think about when writing a good laboratory report:
1) Know your reader. In order to make efficient use of your time when writing a report, you must consider who will be reading your work. In general, this will be your best guide in determining length, content and detail. When writing an engineering report that is directed toward other engineers, you may assume that your reader has knowledge of engineering principles and terminology. However, do not assume that your reader is familiar with the project. In the case of lab instructors, you should assume that they would be looking for a thorough understanding of all aspects of the lab. All questions should be answered and the operation of all circuits explained.
2) Visual impact is important. The appearance of your report is extremely important. If a report is difficult to read, it may receive a lower grade. However, the visual impact of your report means a lot more than that. Think for a moment about how you first look at a magazine article or a textbook. Your eyes are naturally drawn to graphs, drawings, and bold headings. Long pages of closely spaced text usually attract little attention. You should use these natural tendencies to your advantage. Your most important points should be conveyed through diagrams and graphs, supported by the text. If diagrams are not an appropriate method, use bold headings, underline or do something else which makes the most important points or results really stand out.
3) Lure your reader. You should consider one of your main objectives to be to lure your reader further into your work. Your audience will consider very little of what you write as required reading. If no one is interested enough in your writing to read it, you will never get proper credit for the work that you do.
4) Properly label all figures and tables. There are few things worse than seeing neat diagrams or tables in a report with no clue as to what they mean or where they came from. All figures and tables should be numbered and have a caption or title that clearly indicates what they are. Figure and table numbers should start with the number “1” and increase sequentially through the report. More complicated figure numbering schemes, such as those found in a textbook, have no place in a short report. Additionally, ALL circuit diagrams and graphs are by definition figures. Be sure that they are labeled appropriately. If the report does not reference a figure, that figure has no place in your report!
5) Generate high quality output. These days, it is safe to say that all real world documents are being done on computers. All lab reports you write during your time here at UCD are to be computer generated. Some graphs may be done by hand, but they need to be drawn carefully, not sketched. If you use a computer to do your graphs, be sure you use the most appropriate kind. Curve smoothing can emphasize the shape, but obscure details you may wish to reference. Scatter plots, which use curve fitting, are often good ways to see trends, but there are numerous different analytical ways to define the curve, which can also change the meaning of the data. Just because it looks good does not mean it is right!
6) Spelling counts. Over the years, there have been plenty of jokes about engineers and spelling. Poor grammar and bad spelling are unprofessional and detract from your work. With automated spelling checkers in all of the word processing programs, there is no excuse for spelling errors. They make us lazy about checking for syntax errors, however, so be sure you re-read the report to find them.
7) Condense your work. Do not omit any useful detail, but try to communicate your thoughts with the least amount of verbiage possible. (As an example, in the prior sentence, I should have said: “Be complete and concise.”) Use your figure numbers to refer to the diagrams in your report. There is no value in stretching out a report thinking that if it is longer, it will look like more work was done. The most impressive reports always manage to put a lot of information in a relatively short space, while maintaining an easy to read appearance.