Water is known to block or attenuate electromagnetic frequencies (EMF) in the radio wave range, particularly at certain wavelengths. Water molecules strongly absorb frequencies in the range of 2.45 gigahertz (GHz), which is the frequency commonly used in microwave ovens. If you think about it, microwave ovens would be designed to use the frequencies which most heat water, wouldn’t they?
If you think about it a bit more, you may wonder why cell phones use about the same frequencies as microwave ovens.
The 2.4 GHz frequency was selected for cell phone and wifi communications use because it has a longer range and can cover larger areas compared to the 5 GHz frequency. The 2.4 GHz frequency is still widely used for Wi-Fi communications due to its longer range and better signal penetration through solid objects.
Special Water Heating Frequency
Microwave ovens typically operate at a frequency of 2.45 GHz (2450 MHz). This frequency is specifically chosen because it resonates with water molecules, causing them to vibrate and generate heat. Other frequencies, such as 2100 MHz, would not have the same strong effect on water molecules and would not efficiently heat food in microwave ovens. Wifi 802.11 (b/g/n) operates on the 2.4 GHz ISM band, which is the same band that microwave ovens operate on.
What is the cosmic significance of the coincidence that the special frequency that most heats water is the frequency that best penetrates solid objects?
Power Levels
As I sit here looking at one of my EMF meters, specifically at the 2.450GHz band, I see a low but constant signal about -88dBm. Then as if to say hello, something spiked 2.450 GHz up to -73 dBm. This is equivalent to 1.585^-9 mW or 1.585 picowatts (pW) and 5.012E-8 mW or 50.12 picowatts (pW), which is extremely weak compared to the power output of a microwave oven. The wattage of a microwave oven can vary, with typical consumer models ranging from 600 to 1,500 watts.
Type of Water
A search found that salt water, due to its conductivity, can block radio waves of most wavelengths, especially at lower frequencies. However, very low radio frequencies, known as very low frequency (VLF) radiation, can penetrate salt water for a limited distance, typically a few tens of meters.
The absorption of electromagnetic radiation by water depends on the state of the water. For instance, the absorption in the gas phase occurs in three regions of the spectrum, with rotational transitions responsible for absorption in the microwave and far-infrared, and vibrational transitions in the mid-infrared and near-infrared. In the case of liquid water, it has a broad absorption spectrum in the microwave region, which is used in microwave ovens to heat food. Additionally, the search results mention that radiocommunication at GHz frequencies is challenging in both fresh and salt waters.
Summary
Water has a special absorption for 2.450 GHz microwave radiation which is used by some telecommunications equipment. Water, especially salt water, can block or attenuate radio waves at various frequencies, with lower frequencies being more penetrative than higher frequencies. The conductivity and molecular structure of water play a significant role in its interaction with electromagnetic frequencies.
Citations:
[1] https://physics.stackexchange.com/questions/487519/is-salt-water-impervious-to-emf-frequency
[2] https://www.epa.ie/environment-and-you/radiation/emf/what-is-emf/extremely-low-frequency-fields-/
[3] https://www.nature.com/articles/s41545-020-0071-9
[4] https://en.wikipedia.org/wiki/Electromagnetic_absorption_by_water
[5] https://manoa.hawaii.edu/exploringourfluidearth/physical/ocean-depths/light-ocean