# A star sends out a radio wave into space that has a frequency of 5.5 xx 10^7 Hz. What is the wavelength of this radio wave?

Electromagnetic waves travel at a velocity $c$ $\left(m {s}^{-} 1\right)$, and are described by the equation $c = f \lambda$, where $f$ is the frequency $\left(H z = {s}^{-} 1\right)$ and $\lambda$ is the wavelength $\left(m\right)$. Rearranging, $\lambda = \frac{c}{f} = \frac{3.0 \times {10}^{8}}{5.5 \times {10}^{7}} = 5.45$ $m$.