Hello I have a question that is giving me trouble:(adsbygoogle = window.adsbygoogle || []).push({});

Light of wavelength 659.7 nm is emitted by a star. The wavelength of this light as measured on Earth is 661.1 nm.

How fast is the star moving with respect to Earth? km/s

Is it moving toward Earth or away from it?

Here's where I'm at. I have reasoned that since the wavelength is increasing that the star is moving away. My main problem is determining the frequency of the light. I assume that I can use the formula:

velocity = wavelength * frequency

however the frequency I get just seems wrong. The units are throwing me off too, any help would be greatly appreciated.

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# Homework Help: Doppler effect star and earth question

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