MYP Physics · 09 · investigation
Plan a two-source interference test
Waves · Original GioPhysics question with a detailed, mark-by-mark answer guide.
- Demand
- discriminating
- Marks
- 8
- Topics
- 2
- Answer
- Complete
Two coherent ripple sources create alternating regions of large and small amplitude. A student claims that increasing the source separation makes the nodal regions closer together at a fixed distance from the sources.
- a
Formulate State the variables needed to test the claim and one suitable dependent measurement.
3 marks - b
Design Describe a method that would produce evidence strong enough to test the claim.
3 marks - c
Evaluate Explain why judging nodal positions by eye is a limitation and propose a linked improvement.
2 marks
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a
Formulate State the variables needed to test the claim and one suitable dependent measurement.
Turn the task into a measurable method: name the independent, dependent and controlled quantities; describe apparatus and repeats; then explain how the evidence will be processed and how uncertainty or safety will be managed.
- 1
Identifies source separation as the independent variable.
- 2
Identifies nodal spacing at a fixed observation line, or number of nodal lines across a fixed width, as the dependent variable.
- 3
Controls source frequency, water depth, source phase, amplitude, and observation distance.
b
Design Describe a method that would produce evidence strong enough to test the claim.
Turn the task into a measurable method: name the independent, dependent and controlled quantities; describe apparatus and repeats; then explain how the evidence will be processed and how uncertainty or safety will be managed.
- 1
Uses at least five measured source separations and records a frozen or stroboscopic pattern for each.
- 2
Measures across several nodal spacings and divides by the number of intervals, with repeats.
- 3
Plots mean nodal spacing against source separation and uses uncertainty or spread when judging the trend.
c
Evaluate Explain why judging nodal positions by eye is a limitation and propose a linked improvement.
Turn the task into a measurable method: name the independent, dependent and controlled quantities; describe apparatus and repeats; then explain how the evidence will be processed and how uncertainty or safety will be managed.
- 1
Explains that low-amplitude regions have finite width or fluctuate, making the chosen centre subjective.
- 2
Proposes video/image analysis, a fixed grid, or an amplitude probe with a stated threshold to define positions consistently.
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