# Question #680fd

Apr 18, 2017

Let's break this down.

You are given the wavelength ($\nu$) of the wave as $800$ m.

We know that frequency of an electromagnetic wave is just the reciprocal of time taken by that wave to complete one cycle, i.e. the time taken to cover one wavelength.

Let velocity of the wave be $v$. Distance covered by that wave is its wavelength. So we have:

$v = \frac{\lambda}{t}$

Replacing $\frac{1}{t}$ with $\nu$, we get:

$v = \lambda \nu$

We know that the speed of an electromagnetic wave is the well known constant $c$ used to denote the speed of light, whose value is approximately $3 \times {10}^{8}$ metres/second

$3 \times {10}^{8} = 800 \times \nu$

$3.75 \times {10}^{5} = \nu$

Using appropriate units, we get:

$\nu = 3.75 \times {10}^{5} H z$ or $375 k H z$