diffraction grating experiment

diffraction grating experiment
The Discussion of Results section includes an explanation of how the collected data provide logical and reasonable support for the statement found in the Conclusion. The Discussion of Results should be clear, specific, and reasonable. It is often a lengthy section of several sentences and even paragraphs. It is an opportunity for a student to express their understanding of the clear and logical line connecting the evidence (Data section) to the verdict (Conclusion section). In the Discussion of Results section, the student writes, explains, elaborates, supports and cites evidence from the Data section. The student describes how the observations and collected data support the conclusion, citing specific examples as evidence. The student may describe what would have been observed if a contrary conclusion were to be drawn and show how those observations were not made. The student may identify data which seem inconsistent with the conclusion and explain why such data are not swaying the Conclusion in a different direction.

A Discussion of Results section sometimes includes an error analysis. In an error analysis, the student evaluates the reliability of the data. An error analysis is a response to the question “How well did I do?” Expectations or theories (found in textbooks) may be introduced and the consistency between the experimental findings and the theory is discussed. If there is an accepted answer to the question which involves a determined quantity, a percent error calculation is often performed (see bottom of page). If two values are being compared (perhaps a class average of a determined quantity and an individual lab group’s value), a percent difference calculation is often performed (seebottom of page). An error analysis will often identify specific data trials which are in error, describe the manner in which they err from the expected results and attempt to explain the cause of such errors.

here, you show that you understand the experiment beyond the simple level of completing it. Explain. Analyse. Interpret. Some people like to think of this as the “subjective” part of the report. By that, they mean this is what is not readily observable. This part of the lab focuses on a question of understanding “What is the significance or meaning of the results?” To answer this question, use both aspects of discussion:

Analysis Interpretation
What do the results indicate clearly?
What have you found?
Explain what you know with certainty based on your results and draw conclusions: What is the significance of the results? What ambiguities exist? What questions might we raise? Find logical explanations for problems in the data:
Since none of the samples reacted to the Silver foil test, therefore sulfide, if present at all, does not exceed a concentration of approximately 0.025 g/l. It is therefore unlikely that the water main pipe break was the result of sulfide-induced corrosion. Although the water samples were received on 14 August 2000, testing could not be started until 10 September 2000. It is normally desirably to test as quickly as possible after sampling in order to avoid potential sample contamination. The effect of the delay is unknown.
More particularly, focus your discussion with strategies like these:

Compare expected results with those obtained.

If there were differences, how can you account for them? Saying “human error” implies you’re incompetent. Be specific; for example, the instruments could not measure precisely, the sample was not pure or was contaminated, or calculated values did not take account of friction.

Analyze experimental error.

Was it avoidable? Was it a result of equipment? If an experiment was within the tolerances, you can still account for the difference from the ideal. If the flaws result from the experimental design explain how the design might be improved.

Explain your results in terms of theoretical issues.

Often undergraduate labs are intended to illustrate important physical laws, such as Kirchhoff’s voltage law, or the Müller-Lyer illusion. Usually you will have discussed these in the introduction. In this section move from the results to the theory. How well has the theory been illustrated?

Relate results to your experimental objective(s).

If you set out to identify an unknown metal by finding its lattice parameter and its atomic structure, you’d better know the metal and its attributes.

Compare your results to similar investigations.

In some cases, it is legitimate to compare outcomes with classmates, not to change your answer, but to look for any anomalies between the groups and discuss those.

Analyze the strengths and limitations of your experimental design.

This is particularly useful if you designed the thing you’re testing (e.g. a circuit).

Discuss your result
Relate your findings to the theory.
What result did you expect? What did you get? If you got unexpected result what went wrong? How it could have been rectified.
Understanding of the Science
This will mainly be found in the Introduction, Discussion and Conclusion sections. We will be looking for:
Clear explanation of the science underlying your observations. Reasons for experimental method.
Good quality results with units.
Explanations of good or bad results.
Links to theory.
Equations, structural formulae.
Correct mathematical manipulation in calculations, including units. Units on graph axes and/or table headings.
Interpretation of graphs.
Results quoted to correct precision; Consideration of errors.
Again, your ability to use English perfectly is not the main focus of this section – you will gain marks here for showing scientific knowledge and understanding. Note that this section carries the most marks

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