# Math Help - wavelength of radio

Find the wavelength for a typical AM radio with a frequency of 900 kHz?

Find the wavelength for a typical FM radio with a frequency of 99.6 MHz

2. Originally Posted by lovinhockey26
Find the wavelength for a typical AM radio with a frequency of 900 kHz?

Find the wavelength for a typical FM radio with a frequency of 99.6 MHz
I'll use the value of the light speed in vacuum which I have at hand (this value is from 1972 so it may differ a little bit today): $c = 299,792,456\ \frac ms$

Let f denote the frequency and l the wavelength then you know that

$f \cdot l = c$

Plug in the values you already know:

$900 \cdot 10^3\ \frac1s \cdot l = 299,792,456\ \frac ms$

$99.6 \cdot 10^6\ \frac1s \cdot l = 299,792,456\ \frac ms$ . Solve for l.

(For confrmation only: 333.103 m; 3.01 m)