# Writing a Solution to an Experimental Problem

## How to Do It?

Although experimental problems often have general assignments, their solutions should meet certain requirements. In the following paragraphs, we will tell you what a proper solution to an experimental problem should look like.

## Basic Aspects of the Solution

The solution to an experimental problem should have roughly the following parts:

• Introduction
• Considerations and theoretical calculations
• Description of the experimental setup
• Presentation of the measurement results
• Discussion
• Conclusion

This division is not strict, some of the parts can be combined together (e.g. the introduction can flow freely into the theoretical considerations, the discussion can be included in the conclusion, etc.).

#### Introduction

• The introduction should anchor the text in the area of physics covered by the experiment.
• The introduction contains generally known knowledge that is relevant to the experiment and on which the experiment is based.

#### Considerations and Theoretical Calculations

• This section should develop the ideas and basic relationships mentioned in the introduction.
• That is, you are to derive implications for your experiment from commonly known knowledge. Typically, this is, for example, deriving an equation by which a physical system will behave in an experiment.
• However, we sometimes assign experiments where theoretical calculations are too difficult or even impossible. In this case, write down the reasoning behind how the system is likely to behave and what you expect it to do.

#### Description of the Experimental Setup

• This is a very important part of the solution and must not be cheated! In this section you describe the tools used in the experiment and the method of measurement.
• Where relevant, the parameters of the tools used should be quantified (e.g. it is a good idea to give the weight of the pendulum and the weight of the rope, even if we were working in the mathematical pendulum approximation - this has implications for the discussion, where we have to assess whether the mathematical pendulum approximation was correct).
• The execution of the experiment must be described in detail. It must be possible to repeat the measurements according to this description. If it is not clear what tools were used (+ parameters of the tools where it makes sense) and what method was used to make the measurements, you cannot get full marks.
• In this section you can also discuss the inaccuracies of the measuring instruments used.

#### Presentation of Measurement Results

• In most experiments, the key output of the measurement will be a graph. In science and elsewhere in life, graphical presentation of results is desirable. A graph conveys information much more quickly and humanely than a table of numbers.
• Most physics experiments directly encourage the results to be presented graphically (we are measuring the dependence of something on something).
• The axes of the graph must be described with units.
• Do not connect points on the graph with a broken line. Such a broken line has no physical meaning; individual measurements are burdened with errors. Of course, there are exceptions, for example oscilloscope screen recordings or spectral analysis.
• Also, in this section, key results (e.g. fitting line directives) should be determined or calculated from the measured data, including errors.
• For more detailed instructions on graphical processing of measured data, see the Graphical Data Processing Basics page.

#### Discussion

• In this section, think about the plausibility of the results, and systematic errors affecting the accuracy of the measurements. If you did not calculate measurement uncertainty in the previous section, do so here. You need to understand what limits the accuracy of its measurement.
• Next, you should compare the results of the experiment with your theoretical reasoning and calculations and, if possible, with values from tables or scientific publications.
• If you cannot calculate the uncertainty of the result, at least try to estimate it.
• You can, of course, suggest other experiments that would further deepen your work or give more accurate results.

#### Conclusion

• The conclusion should summarise the most important findings from the experiment. It should again explicitly state the key results of the measurements and their uncertainties.
• It should also state whether the results of the experiment are consistent (qualitatively or quantitatively) with the predictions made in the „Considerations and Theoretical Calculations“ section.
• Just a few sentences are enough, the conclusion should really only highlight the most important points.

For a more detailed explanation, commentary, guidelines and examples, see the recommended literature, e.g. you can find instructions in Czech language B. Vybíral: Zpracování dat fyzikálních měření (FO).

## How Do I Get a Bonus Point for the Experimental Task?

• The prerequisite for getting the bonus point is to complete the experimental problem and the written solution for the full number of points (see above), otherwise we will only add a point to your solution. We may award a bonus point for e.g. an original, ingenious measurement method or the use of such a tool. 