- #1
How Do You Determine the Phase of Waves from a Diagram?
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Homework Help Overview
The discussion revolves around determining the phase of waves from a diagram, specifically analyzing how to extract values from a graphical representation of wave functions.
Discussion Character
- Exploratory, Conceptual clarification, Assumption checking
Approaches and Questions Raised
- Participants explore how to interpret the y-intercept of the wave diagram and its relation to the sine function's values. Questions arise about the angles corresponding to specific amplitudes and how to derive phase information from the graph.
Discussion Status
Several participants are engaged in examining the graphical data, with some suggesting specific angles and discussing their implications. There is an ongoing exploration of the relationship between the wave's graphical features and the sine function, but no consensus has been reached on the correct interpretation of the phases.
Contextual Notes
Participants note that the options for phase values presented in the problem do not align with their interpretations, leading to further questioning of the assumptions made based on the diagram.
- #2
collinsmark
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Look at the y-intercept. Each wave crosses the y-axis exactly halfway between the origin and the wave's maximum amplitude. What sort of "angle" causes the sine function to be half its maximum amplitude?jegues said:
- #3
jegues
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collinsmark said:Look at the y-intercept. Each wave crosses the y-axis exactly halfway between the origin and the wave's maximum amplitude. What sort of "angle" causes the sine function to be half its maximum amplitude?
I know the angle you're talking about is 30 degrees.
When I look at it, it looks like the first wave has a phase of -45 degrees and the second a phase of -135 degrees, but those options aren't present...
Because at 45 degrees it would be half way to reaching its maximum value at 90 degrees.
- #4
SammyS
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Look at the distance (on the x-axis) from the x-intercept to the x value of the maximum. Then compare that and where the y-intercept is (x=0). Looks to me like x=0 is about 1/3 the distance from the x-intercept to x of the max. 45° is halfway from the x-intercept to where Sine has it's max. The value of sine(45°) = 1/√(2) ≈ 0.707. The y-intercept does not look (to me) like it's close to being 70% of the max value.jegues said:
If collinsmark is talking about 30°, then he knows what he's talking about! Where else is sin(θ) = 1/2 ?