The frequency of an electromagnetic wave can be calculated using the formula:
Frequency = Speed of Light / Wavelength
The speed of light is approximately 299,792,458 meters per second.
For a wavelength of 25 meters: Frequency = 299,792,458 meters per second / 25 meters ≈ 11,991,698 hertz (or 11.99 megahertz)
For a wavelength of 75 meters: Frequency = 299,792,458 meters per second / 75 meters ≈ 3,997,565 hertz (or 3.99 megahertz)
Please note that these calculations assume the wave is propagating in a vacuum, as the speed of light used is the speed in a vacuum. In different mediums, the speed of light is slightly slower, which would affect the frequency calculation accordingly.