Question

If light moves and 300, 000m / s in a vacuum what would be the wavelength of a light wave that has a frequency of 40,000Hz in outer space ?

Answer 1

$\begin{gathered} given: \\ frequency\text{ }\vartheta=40,000\text{ Hz} \\ speed\text{ of light c=3*10}^8\text{ m/s} \end{gathered}$$\begin{gathered} to\text{ find:} \\ wavelength\text{ }\lambda=? \end{gathered}$$\begin{gathered} wavelength\text{ }\lambda=\frac{v}{\vartheta} \\ v=speed\text{ of the wave} \end{gathered}$$\begin{gathered} put\text{ the values in the above formula} \\ \lambda=\frac{3*10^8m/s^2}{40000Hz} \\ \lambda=0.75*10^4m \end{gathered}$

so the value of wavelength λ=0.75*10^4 m