Standard Experiment Report GN00

Standard experiment report GN00

(Alex Wyld, 08/10/2009)

Abstract contains a short statement that gives the object of the investigation and its results (including experimental uncertainties). Its purpose is to catch the eye of the person riffling through the pages of a scientific journal allowing him or her to decide quickly if the article is relevant. It is similar to the conclusions and is normally written at the last stage of the report. In the First Year lab reports abstract would normally contain around 5 lines of text. The font is 10pt Justified. The body of the abstract is also indented (by 1cm with respect to the main text) on both sides of the paragraph.

Introduction

A good introduction leads the reader into the report and encourages him or her to read further. It should contain all the relevant background to the investigation so that the ‘theory’ section can be read with understanding. Typically it includes the history of the previous work and the reasoning for the current experiment. From the introduction the reader should clearly see the aim of the experiment. When citing previous work a proper reference should be given [1]. The content of the introduction should be concise, 10-15 lines of text. The font size is 12pt for the rest of the text in the report.

Theory

This section should contain all the important definitions and all the principle equations used in interpreting and analysing the experiment. Brief derivations should be given if possible, particularly when a non-standard equation is used. If a derivation is lengthy it is usual to give a reference to a book [1] or to an article [2] in a scientific journal in which the interested reader may follow up the matter. All the basic concepts on which the experiment is based should be mentioned somewhere in this section. This section could be combined with the introduction. Very often the theory section would contain formulae. There are two ways of presenting these in the report. Either by simply inserting them within the text, like this: , or by sub setting the formula within the paragraph, like this:

(1)

In the later case it is a normal practise that a number is assigned for purpose of referencing within the text. It is also important (a universal rule for all scientific publications), that all the variables in the formulas are defined the very first time they come across in the text.

Experimental

This part should indicate concisely the actual way in which the experiment was carried out. It describes the method and the techniques involved. In the first year laboratories a particular requirement will be to include here a list of the equipment and the diagram showing schematically the experimental set-up. For instance in case of a Hooks law experiment these components can be presented in the following way:

1) Instrumentation

i) Weights of different nominations (50g, 100g, 150g, 200g +/- 1g)

ii) Ruler on a vertical support (scale precision +/- 1mm)

iii) Spring Support

iv) Spring (Initial length L=30.0 +/- 1mm)

2) Diagram of the experimental setup

Spring
Ruler

Weight

Fig.1. Schematic diagram of the measurement. The ruler is placed in close proximity to the disk (weight). The spring extension is determined by levelling the disk surface with the scale marks.

Note, the essential component of any figure is its caption. As a rule (for scientific publications) the caption is placed below the figure, and numbered using notations as shown in figure 1. The main purpose of the caption is to detail the information in the figure. This may include naming separate components or explaining their actions during the experiment.

A particular aspect of the report, which will be specifically observed in the First Year laboratories, is dealing with the uncertainties of measurements. In particular, when listing the instrumentation it is a good practise to include the measured values of various components (e.g. the weights parameters) with the uncertainty associated with that value (i.e. +/- 1g). These initial uncertainties are then used to derive the error of the whole experiment.

Plan of Measurements

This section is normally a constituent of the experimental part in scientific publications. It describes the plan of measurements and procedures used to obtain a particular result. In the first year laboratories reports the focus should be given not as much to the details (which are normally given in the experiment descriptions), rather to the whole sequence of events involved in the measurement. This section should not include more than 10-15 lines (depending on the experiment). For example for the above case of Hooks law the plan of measurements may look like this:

1) Identify the zero level (unstressed spring) position

2) Measure the extension of the spring for different masses

3) Plot the dependence of the extension versus the value of the weight

4) Fit a linear function to the experimental data points

5) Identify the gradient of the inclination

6) Derive the error of the gradient

This section should also include the expectation of the error of the result in question. The focus should be given to the factors contributing to the error rather than the actual value.

Safety Procedures

Briefly describes potential hazards and safety procedures involved in the experiment.

Results

This section includes the obtained final results together with the errors. Any plots, diagrams and data tables should be given here. For the first year laboratory reports all the raw data and the calculations leading to the results must be present in the lab book. Make sure that the links between the information in the lab book and the report are clear, so that the assessors can easily find the source of the results.

GRAAAAAAPH

Fig.2. Extension of the spring as a function of the attached weight (red circles) along with a fit of linear regression (blue line). Note the axes labelling. (To plot this follow the instructions here [3])

As described previously any plots or tables should be properly annotated with the captions (as shown in figure 2). As noted below probably the most important part of the result is the information about the error. Understanding and treating the propagation of errors is the hardest part of the results.

Discussion

Discusses the outcome of the experiments in the context of initial expectation, e.g. comparison with already known values or constants measured in the experiment should be given. Discusses the source and significance of errors. Suggests an advice for further improvements or alternative methods. No limit in the volume, however not less than 5-10 lines of text).

Conclusions

The conclusions section is similar to the abstract in that it is frequently turned to first by the scientific browser. It should therefore state concisely the overall result of the experiment and summarise the findings of the discussion section.

Reference

Reference must be made wherever an equation, figure or idea has been obtained from an external source. References are usually cited in order to fill gaps in the exposition of a scientific article: detailed development of theory, detailed description of an experimental technique etc. The cited material is listed on its own section in a way that depends on the nature of the source: if a book then the sequence Author(s), Title, Publisher, Year of publication is used; if a journal article then Author(s), Name of journal/Volume, Page, Year; if a web page, then the URL and the date on which it was accessed should be stated. Examples of typical entries are given here:

[1] Young H.D. and Freedman R.A. (2007), University Physics (with Modern Physics) (12th edition), Addison-Wesley, ISBN 0-321-50131-4 (UL: 530 YOU)

[2] Vukusic P, Science, 325 398 2009

[3] (1/10/2009)