Radio Waves
Radio waves have a longer wavelength than visible light, and includes AM/FM radio, microwaves, cell phones, radar, and many remote controlled devices. The longer waves do not react quite as quickly, which allows them to penetrate deeper into the body until their energy is finally used up. Think of a microwave oven that heats food inside-out, instead of just scorching the surface.
To get a better picture of how waves interact with objects, consider a radio antenna. The antenna is made of a metallic conductor that is easily influenced by radio waves. As the electromagnetic wave passes over the antenna, the electric portion of the wave (in this example) has, of course, an electrical charge that changes according to which part of the wave is touching it at a given time. That charge pushes or pulls electrons in the antenna, creating a small electric current which is then processed by the receiver connected to the antenna.
Creation of a current in a dipole antenna by a radio wave.
Antenna design is a science in its own right, but basically involves using the correct length and orientation to best match the wave to maximize the electron flow.
The effect is very similar to the way a static charge builds up while shuffling your feet in low humidity, when your hair stands up on end or you get a shock when touching metal objects.
So why am I going through all this here? Because cells in the body can act like crude antennas to convert the energy of these waves into something constructive (as in our Suntans example) or more often, something that interferes with the normal function of the body, particularly in nerve cells.