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## Homework Statement

Superman is carrying a red lantern with wavelength 650nm. He flies toward you at a speed of 2.7x108 m/s.

What is the observed wavelength?

## Homework Equations

[itex]f'=\frac{f}{\left(1-\frac{v_s}{v}\right)}[/itex]

and

[itex]f=\frac{c}{\lambda}[/itex]

## The Attempt at a Solution

I used the equation [itex]f'=\frac{f}{\left(1-\frac{v_s}{v}\right)}[/itex] and got my answer to be [itex]65[/itex] nm. What did I do wrong?

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