Physics Extended Essay Example: Magnetic Pendulum Angular… | RevisionDojo

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IB Physics SL Extended Essay Example

How does varying the initial angular displacement of a magnetic pendulum affect its stopping time due to damping caused by the eddy currents induced in the copper plates below it when the string used for the pendulum, the magnet used, the dimensions of the copper plate, and the magnetic field strength of the magnet are kept controlled?SL

Official IB Result

16/34

Criteria A: Focus and Method

4/6

Criteria StrandsPro

A.1Topic clarity and communication

Good

A.2Research question formulation and focus

Good

A.3Methodology appropriateness and completeness

Moderate

Criteria Feedback

The student identifies a relevant physics topic and communicates the investigation purpose clearly enough for the reader to follow the practical aim.
The student's research question is specific and experimentally testable, with the independent and dependent variables made visible in the design.
The method shows real practical work through repeated trials, a defined angle range, and supporting data/photos.

The dependent variable is not operationally defined with enough precision, so the point at which the bob is considered to have stopped remains subjective.
The investigation is not fully focused because it does not include a no-copper control to separate eddy-current damping from other sources of damping.
Some key methodological details are missing, such as calibration, uncertainty treatment, and how consistency of release and plate separation were maintained.

1.1·Strength

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The research question is clearly stated and experimentally testable. The student identifies the independent variable, dependent variable, and key controls in one sentence, which gives the investigation a clear direction and makes the later method and data collection easier to follow.

1.2·Question

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What evidence shows that a plot of angle against stopping time actually quantifies energy lost per oscillation, rather than only a time trend? Clarifying that reasoning would make the purpose of the investigation much sharper.

1.3·Weakness

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The discussion here is too broad because it treats “stopping time” as if it were a directly physical quantity without defining when motion counts as stopped. The student should set an explicit threshold, such as a minimum measurable amplitude or velocity, so the dependent variable is objective and reproducible.

1.4·Weakness

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This claim weakens the focus because it introduces an unsubstantiated link between

k_{d}

and the period. The student should justify this with a derivation or remove it, since an unsupported proportionality can make the whole model appear arbitrary.

1.5·Suggestion

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Consider defining this variable more precisely in the method, for example as the time until the bob’s amplitude falls below a chosen threshold. A precise operational definition would make the research question and data collection more scientifically robust.

1.6·Weakness

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The range is quite narrow for a claim about proportionality. Extending the angles or explaining why this window was chosen would improve focus, because it would show whether the relationship still holds beyond the limited low-amplitude region tested.

Criteria B: Knowledge and Understanding

4/6

Criteria StrandsPro

B.1Subject knowledge application

Moderate

B.2Use of terminology and concepts

Moderate

Criteria Feedback

The student uses appropriate physics language in many places, including terms such as eddy currents, Lenz’s law, damping, and angular frequency.
The theoretical background shows a genuine understanding of electromagnetic induction and how it relates to the apparatus the student built.
The student generally applies subject knowledge to the investigation context rather than keeping it abstract.

Some terminology is used imprecisely, especially where damping constants, damping ratios, and underdamping are mixed together.
There are places where the mathematics is not fully secure, such as unsupported proportionality statements and inconsistent interpretation of graphs.
The report sometimes shifts between different quantities without keeping the physical meaning clear, which weakens the accuracy of the explanation.

2.1·Strength

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The student demonstrates sound foundational knowledge by defining induction, eddy currents, and Lenz’s law in connected terms. This helps establish a credible theoretical basis for the investigation rather than presenting the topic as a collection of isolated facts.

2.2·Strength

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This is a strong application of subject knowledge because the student correctly adapts the general induction diagram to the actual apparatus. That transfer from a textbook model to the experiment shows good understanding of how eddy currents arise in the chosen setup.

2.3·Weakness

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The variables are named, but the relationship is presented as if it were established physics without sufficient support or dimensional justification. The student should explain where this form comes from, because otherwise the equation reads more like an assumption than a defensible model.

2.4·Question

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If the relationship is truly direct proportionality, why does the later graph include a non-zero intercept of 4.98 s? Addressing that inconsistency would improve both the physics and the credibility of the claim.

2.5·Weakness

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The mathematical interpretation here is not secure. The student should separate the calculation of the gradient from the explanation of what it means, and use correct notation for the relationship rather than introducing a partly written and unexplained proportionality.

2.6·Weakness

Page 30• Click to view

The terminology here is inaccurate: underdamping is usually described using a damping ratio, not a negative value of

\gamma

. The student should distinguish the decay constant from the dimensionless condition for underdamping, because mixing them weakens the physics explanation.

Criteria C: Critical Thinking

4/12

Criteria StrandsPro

C.1Research analysis and evaluation

Poor

C.2Discussion and argument development

Poor

C.3Critical evaluation

Poor

Criteria Feedback

The student collects repeated measurements and attempts to identify a clear empirical trend in the data.
The student includes relevant evaluation points and shows awareness of several sources of error and limitation.
The student makes an effort to connect the results, graphing, and conclusion into one argument.

The analysis does not sufficiently test whether the relationship is reliable, because there is little quantitative treatment of spread, uncertainty, or statistical significance.
The conclusion goes beyond what the evidence can support by treating a fitted trend as stronger proof than it really is.
The evaluation remains more descriptive than critical, since several limitations are listed but not fully explained in terms of their effect on validity.

3.1·Strength

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The raw data table is a strong feature because it shows seven trials for each angle, which gives the investigation repeatability and allows the student to identify patterns rather than rely on a single measurement at each setting.

3.2·Weakness

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The high

R^{2}

value is useful, but the analysis does not show uncertainty, spread, or any test of whether the trend is statistically meaningful. The student should add measures such as standard deviation or error in the mean, because a good fit alone does not establish reliability.

3.3·Strength

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The student attempts to explain the small horizontal error bars rather than leaving the graph uninterpreted. That is good analytical practice because it shows awareness that graphs need contextual explanation, not just plotted points.

3.4·Weakness

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This theoretical line is generated from the experimental trendline, so the perfect

R^{2}

does not actually validate the model. The student should make clear that a fitted line based on the same data is not independent evidence, otherwise the analysis becomes circular.

3.5·Weakness

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This point is too general and does not evaluate the evidence against the research question. The student should explain exactly how repeatability improved the result, and whether the repeated trials actually reduced random error or just confirmed the same pattern.

3.6·Weakness

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This is an important limitation, but it is not pushed far enough. The student should state how these uncontrolled damping sources may have altered the stopping times and how that affects the validity of the conclusion, not just list them.

3.7·Suggestion

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This is a practical improvement, and it could be strengthened further by explaining how video analysis would be used consistently across all trials. Linking the tool to a specific procedure would make the evaluation more actionable.

3.8·Question

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Does a linear fit by itself prove direct proportionality, or could it also reflect the limited range of angles tested? This is worth reconsidering so the conclusion matches the strength of the evidence.

Criteria D: Presentation

2/4

Criteria StrandsPro

D.1Structure and formatting

Good

D.2Layout and visual elements

Good

Criteria Feedback

The report is generally readable and follows a recognisable scientific structure.
Figures, tables, and photographs are included to support the written explanation.
The document is mostly navigable, with page numbers and a clear overall organisation.

Some section headings and labels are inconsistent or inaccurate, which reduces polish and clarity.
Several visual elements need clearer explanation, especially where graph lines or error bars are not self-evident.
The presentation would be stronger with more consistent attribution and tighter alignment between the contents page, headings, and references.

4.1·Weakness

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The heading under the contents list is inconsistent with the rest of the report, where the section is later titled “Acknowledgements.” The student should use one spelling and one heading style throughout so the structure looks deliberate and professionally edited.

4.2·Strength

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The report is easy to navigate because it includes a clear contents page and a logical sequence of sections. This supports presentation by helping the reader locate the introduction, method, analysis, and conclusion efficiently.

4.3·Strength

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The method is presented in a step-by-step sequence that is detailed enough for another student to follow. That level of procedural clarity improves presentation because the investigation is reproducible, not just descriptive.

4.4·Suggestion

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Consider adding a brief note in the main text explaining how the diagram helps the reader interpret the apparatus. A short link between the figure and the method would make the layout more integrated and purposeful.

4.5·Weakness

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This heading does not match the calculation that follows, which is actually an average time. The student should rename it accurately, because misleading section labels reduce clarity and make the report harder to trust.

4.6·Weakness

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The graph labels are not self-explanatory here. If the student wants to distinguish multiple lines, the legend should clearly identify what each line represents so the visual evidence can be interpreted without guesswork.

4.7·Weakness

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This explanation is too absolute and reads as an unsupported claim. The student should state the actual instrument uncertainty and show how it was used to determine the error bars, rather than asserting that the errors are insignificant.

Loading scores...

Official IB Result

16/34

Criteria A: Focus and Method

4/6

Criteria StrandsPro

A.1Topic clarity and communication

Good

A.2Research question formulation and focus

Good

A.3Methodology appropriateness and completeness

Moderate

Criteria Feedback

The student identifies a relevant physics topic and communicates the investigation purpose clearly enough for the reader to follow the practical aim.
The student's research question is specific and experimentally testable, with the independent and dependent variables made visible in the design.
The method shows real practical work through repeated trials, a defined angle range, and supporting data/photos.

The dependent variable is not operationally defined with enough precision, so the point at which the bob is considered to have stopped remains subjective.
The investigation is not fully focused because it does not include a no-copper control to separate eddy-current damping from other sources of damping.
Some key methodological details are missing, such as calibration, uncertainty treatment, and how consistency of release and plate separation were maintained.

1.1·Strength

Page 7• Click to view

1.2·Question

Page 7• Click to view

1.3·Weakness

Page 8• Click to view

1.4·Weakness

Page 9• Click to view

This claim weakens the focus because it introduces an unsubstantiated link between

k_{d}

and the period. The student should justify this with a derivation or remove it, since an unsupported proportionality can make the whole model appear arbitrary.

1.5·Suggestion

Page 11• Click to view

1.6·Weakness

Page 12• Click to view

Criteria B: Knowledge and Understanding

4/6

Criteria StrandsPro

B.1Subject knowledge application

Moderate

B.2Use of terminology and concepts

Moderate

Criteria Feedback

The student uses appropriate physics language in many places, including terms such as eddy currents, Lenz’s law, damping, and angular frequency.
The theoretical background shows a genuine understanding of electromagnetic induction and how it relates to the apparatus the student built.
The student generally applies subject knowledge to the investigation context rather than keeping it abstract.

Some terminology is used imprecisely, especially where damping constants, damping ratios, and underdamping are mixed together.
There are places where the mathematics is not fully secure, such as unsupported proportionality statements and inconsistent interpretation of graphs.
The report sometimes shifts between different quantities without keeping the physical meaning clear, which weakens the accuracy of the explanation.

2.1·Strength

Page 3• Click to view

2.2·Strength

Page 6• Click to view

2.3·Weakness

Page 8• Click to view

2.4·Question

Page 10• Click to view

2.5·Weakness

Page 20• Click to view

2.6·Weakness

Page 30• Click to view

The terminology here is inaccurate: underdamping is usually described using a damping ratio, not a negative value of

\gamma

. The student should distinguish the decay constant from the dimensionless condition for underdamping, because mixing them weakens the physics explanation.

Criteria C: Critical Thinking

4/12

Criteria StrandsPro

C.1Research analysis and evaluation

Poor

C.2Discussion and argument development

Poor

C.3Critical evaluation

Poor

Criteria Feedback

The student collects repeated measurements and attempts to identify a clear empirical trend in the data.
The student includes relevant evaluation points and shows awareness of several sources of error and limitation.
The student makes an effort to connect the results, graphing, and conclusion into one argument.

The analysis does not sufficiently test whether the relationship is reliable, because there is little quantitative treatment of spread, uncertainty, or statistical significance.
The conclusion goes beyond what the evidence can support by treating a fitted trend as stronger proof than it really is.
The evaluation remains more descriptive than critical, since several limitations are listed but not fully explained in terms of their effect on validity.

3.1·Strength

Page 17• Click to view

3.2·Weakness

Page 19• Click to view

The high

R^{2}

3.3·Strength

Page 19• Click to view

3.4·Weakness

Page 22• Click to view

This theoretical line is generated from the experimental trendline, so the perfect

R^{2}

does not actually validate the model. The student should make clear that a fitted line based on the same data is not independent evidence, otherwise the analysis becomes circular.

3.5·Weakness

Page 24• Click to view

3.6·Weakness

Page 24• Click to view

3.7·Suggestion

Page 26• Click to view

3.8·Question

Page 30• Click to view

Criteria D: Presentation

2/4

Criteria StrandsPro

D.1Structure and formatting

Good

D.2Layout and visual elements

Good

Criteria Feedback

The report is generally readable and follows a recognisable scientific structure.
Figures, tables, and photographs are included to support the written explanation.
The document is mostly navigable, with page numbers and a clear overall organisation.

Some section headings and labels are inconsistent or inaccurate, which reduces polish and clarity.
Several visual elements need clearer explanation, especially where graph lines or error bars are not self-evident.
The presentation would be stronger with more consistent attribution and tighter alignment between the contents page, headings, and references.

4.1·Weakness

Page 2• Click to view

4.2·Strength

Page 2• Click to view

4.3·Strength

Page 12• Click to view

4.4·Suggestion

Page 14• Click to view

4.5·Weakness

Page 18• Click to view

4.6·Weakness

Page 19• Click to view

4.7·Weakness

Page 22• Click to view