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Speed inorder to shift green light to blue light?

by Moviemann345
Tags: blue shift, doppler effect, light, speed, wave
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Moviemann345
#1
Jul31-10, 11:44 PM
P: 24
Hypothetically if your in a jet or spaceship & are shining a green laser pen out the window how fast must you travel to cause the green light (570 nm) to change into low energy blue light (475 nm)
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Doc Al
#2
Aug1-10, 06:55 AM
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Look up the Doppler effect.
Moviemann345
#3
Aug1-10, 10:04 AM
P: 24
fo = fv/(v vs)? This isn't a hw problem & im not in a physics class, I was just curious

Doc Al
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Aug1-10, 10:14 AM
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Speed inorder to shift green light to blue light?

Quote Quote by Moviemann345 View Post
fo = fv/(v vs)? This isn't a hw problem & im not in a physics class, I was just curious
You need to use the relativistic Doppler formula:

[tex]f_o = f_s \sqrt{\frac{1 + \beta}{1 - \beta}}[/tex]

where β = v/c

Solve for β, then you'll have the speed. To convert wavelength to frequency, use c = fλ.

This tells you the frequency shift seen by an observer when the light source moves toward him at speed v.
Moviemann345
#5
Aug1-10, 10:33 AM
P: 24
Oh ok thanks I'll try it out


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