List three kinds of electromagnetic radiation and either how it is used or how it is prevented

-- Electromagnetic radiation with frequencies between 20 KHz and 80 GHz is generically referred to as "radio waves" and used for "radio" communication.

-- Electromagnetic radiation with frequencies around 2.6GHz (in the US) is used to warm up leftover meatloaf or chicken, or to cook still other foods from scratch.  This radiation is often called "microwave", but technically, "microwave" is actually radio waves with frequencies greater than 3GHz. So the kitchen appliance misses using 'microwaves' by a little bit. (In the US.  "Microwave" cooking appliances in other countries use different frequencies.)

-- Electromagnetic radiation with wavelengths between roughly 400-750 nm is called "visible light".  It is widely used to see stuff with, since human eyes are very effective detectors of this radiation, and we normally have them with us wherever we go.  

-- Electromagnetic radiation with wavelengths less than roughly 400 nm includes ultraviolet rays, X-rays, and gamma rays.  The shorter it is, the more penetrating it is, and the more dangerous it is to human tissue.  

We protect ourselves against exposure to this radiation with a variety of barriers, comprised of thicker and more dense materials as the wavelength decreases and the danger increases.  

Examples include clothing and sunscreen (for ultraviolet rays), thin layers of lead (for X-rays), and thick layers of lead and concrete (for gamma rays).

electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia