Basic problem regarding doppler effect of light (E/M waves)

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Homework Help Overview

The discussion revolves around a problem related to the Doppler effect of light, specifically how the wavelength of red light (630 nm) can be perceived as green light (530 nm) based on the relative speed between the observer and the source of light.

Discussion Character

  • Exploratory, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants discuss the application of the Doppler effect formula to determine the necessary speed for the observed wavelength shift. There are attempts to solve for the velocity using the provided equation, and questions arise regarding the correctness of the approach and calculations.

Discussion Status

Multiple participants have shared their calculations for the velocity, with slight variations in their results. There is acknowledgment of the formula used and a general agreement on the method, although no explicit consensus on the final answer has been reached.

Contextual Notes

The discussion is framed within the context of a homework assignment, and participants are navigating the complexities of the Doppler effect as it pertains to light, with some uncertainty about the calculations and assumptions involved.

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"Basic" problem regarding doppler effect of light (E/M waves)

1. At what speed would one have to move at to see a red light as green. Presume red light wavelength = 630nm and green light wavelength = 530nm.



2. f0=fs√([1+v/c]/[1-v/c])
>f0 = observed frequency
>fs = source frequency
>v = velocity relative of source and observer
>c = speed of light (3.0e8)



The Attempt at a Solution


Our professor said we only need that equation to solve the proble, we were just introduced to the topic of light, relavitiy, and polarization (our chapter is on doppler effect). I assume that to get the answer you solve for v and plug the rest in, but that's been harder than i expected. Is there another formula i can use in combination with the one given or am i just not solving for v right...? thanks.
 
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Square both sides and solve the linear equation for v
 


i did that... would anyone mind checking my answer?

v=[(c)(f0/fs)2-c] / [(f0/fs)2+1]

and my final answer for v was 5.14 x 107 m/s, towards the source because the wavelength shifts from the source, 630nm, to that observed, 530nm, a blue shift...?
 


I got v = 5.13 x 107 m/s but that's a minor detail =) since the formula is the same
 


sweet... thanks
 

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