Radio waves, including those used in cell phone communication, travel at the speed of light in a vacuum, which is approximately 299,792 kilometers per second (186,282 miles per second). In practical terms, when radio waves propagate through the Earth's atmosphere, their speed is slightly slower due to interactions with the medium, but it is still extremely fast.
Regarding the second part of your question, radio waves, including those emitted by cell phones, are non-ionizing radiation. This means they do not have enough energy to remove electrons from atoms or molecules, which is what ionizing radiation, such as X-rays or gamma rays, can do. As a result, radio waves do not pose a significant risk of causing direct harm or electric shocks to the human body, even when cell phones are in close proximity.
When radio waves encounter the human body, they can interact with it in several ways. These interactions depend on the frequency of the radio waves, the distance from the source, and the composition of the body.
Absorption: Some radio waves can be absorbed by the human body, especially at certain frequencies. The energy from absorbed radio waves is converted into tiny amounts of heat, but it is generally not sufficient to cause any harm or discomfort.
Reflection: Radio waves can be reflected off the body's surfaces, similar to how light reflects off a mirror. This reflection allows radio waves to bounce off and change direction, but they do not penetrate deeply into the body.
Transmission: At certain frequencies, particularly those used by mobile communication, radio waves can pass through the body to some extent. However, they do not penetrate deeply like X-rays. Instead, they tend to pass through tissues without causing significant effects.
It's important to note that while the radio waves emitted by cell phones are considered safe, it is still recommended to follow established guidelines and maintain safe distances from the body during device usage, as provided by regulatory bodies and manufacturers. These guidelines are designed to ensure minimal exposure and account for potential variations in individual sensitivities or health conditions.