What happens to wavelength and frequency when a wave changes velocity

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Discussion Overview

The discussion centers on the behavior of electromagnetic (EM) waves as they transition into a denser medium, specifically focusing on how their wavelength and frequency change with velocity. The scope includes conceptual understanding and mathematical relationships related to wave behavior in different media.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant questions whether the frequency of an EM wave remains constant while its wavelength changes when entering a denser medium, suggesting that the wave may become compressed.
  • Another participant provides a mathematical relationship involving the index of refraction and the change in wavelength, indicating that this relationship offers a straightforward answer to the initial question.
  • A different participant describes a graphical approach to understanding the phenomenon, suggesting that the first part of the wave slows down upon entering the denser medium, leading to a bunching effect of the waves.
  • A later reply expresses appreciation for the visual explanation and indicates a preference for visual understanding before applying mathematical verification.

Areas of Agreement / Disagreement

Participants express varying approaches to understanding the changes in wavelength and frequency, but there is no explicit consensus on the implications of these changes or the effects on amplitude.

Contextual Notes

The discussion includes assumptions about the behavior of waves in different media and relies on specific definitions related to the index of refraction and wave properties, which may not be universally agreed upon.

Who May Find This Useful

Readers interested in wave mechanics, electromagnetic theory, or those seeking to understand the interaction of waves with different media may find this discussion relevant.

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When an EM wave goes into say a denser medium and its velocity is decreased how does its wavelength and frequency change? I read that the frequency remains constant but the wavelength changes. Is this true? If so does that mean the wave gets compressed when it enters a denser medium. Does the amplitude decrease too?
 
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The index of refraction specifically states the change in wave-length for a em-wave.

n=\frac{\lambda}{\lambda_{n}}

and the relation for velocity-a medium- and light is

n=\frac{c}{v}

that gives a simple answer to your question. does it help?
 
Or if you wish to think of it "graphically" then imagine a wave heading into an object, say glass at a specific angle. What happens to the first part of the wave that hits the glass?... you can think of it like the first part of the wave gets slowed down, before the other part catches up. Now draw this, and you'll notice that the waves tend to get bunch up. Now make deductions based on the fact that you know the velocity has decreased.
 
Ah yeah that explains it thanks. I do like to understand things visually first then use the mathematical approach to verify my understanding and unravel things I wouldn't have spotted.
 

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