Question

Am radio signals have frequencies between 550 khz and 1600 khz (kilohertz) and travel with a speed of 3.00 ✕ 108 m/s. what are the wavelengths of these signals?

Answer 1

The minimum frequency is 
$f_1 = 550 kHz = 5.50 \cdot 10^5 Hz$
while the maximum frequency is
$f_2 = 1600 kHz = 1.6 \cdot 10^6 Hz$
Using the relationship between frequency f of a wave, wavelength $\lambda$ and the speed of the wave v, we can find what wavelength these frequencies correspond to:
$\lambda_1 = \frac{v}{f_1}= \frac{3 \cdot 10^8 m/s}{5.5 \cdot 10^5 Hz}=545 m$
$\lambda_2 = \frac{v}{f_2}= \frac{3 \cdot 10^8 m/s}{1.6 \cdot 10^6 Hz}=188 m$

So, the wavelengths of the radio waves of the problem are within the range 188-545 m.