2.1 electromagnetic radiation

• radiation: energy emitted in the form of particles or waves
• electromagnetic radiation (emr): a wave that consists of a changing electric field and a changing magnetic field travelling at right angles to one another
• transverse wave: a wave in which the vibrations are perpendicular to the direction the wave is travelling
• cycle: one complete vibration of a wave
• wavelength: the distance from a point on one wave to the corresponding point on the next wave; the length of one cycle
• frequency: the number of cycles per second
• hertz: the unit for frequency (Hz)
• electromagnetic spectrum: the wide band of different types of electromagnetic radiation ranging from radio waves to gamma rays
• radio wave: a type of electromagnetic radiation with a frequency less than 3000 GHz; used primarily for communications
• antenna: a transmitter or receiver of electromagnetic energy
• extremely low frequency (ELF): electromagnetic radiation with a frequency between 3 and 300 Hz; emitted from power distribution cables
• magnetic resonance imaging (MRI): a method of obtaining internal images of object, especially living organisms, by using radio waves and strong magnetic fields
• microwaves: a type of electromagnetic radiation with a frequency between 1 GHz and 100 GHz; used for radar, satellite communications and cooking food
• infrared light/infrared radiation: a type of electromagnetic radiation with a frequency between 3.0x10^11 Hz and 4.3x10^14 Hz, that increases the vibrations between molecules, resulting in heating effects
• beaming: the communication of data between wireless devices using a beam of infrared light
• visible light spectrum: the complete range of all colours of light visible to the human eye; red, orange, green, blue, indigo and violet, frequencies range from 4.3x10^14Hz to 7.5x10^14 Hz
• photon: a small bundle of electromagnetic energy
• ultraviolet light/radiation (UV): a type of electromagnetic radiation that is emitted by very hot objects; frequencies range from 7.5x10^Hz to 1x10^18 Hz
• ionizing radiation: high-energy radiation capable of ionizing the material through which it masses, leading to the formation of free radicals
• x-rays: high-energy electromagnetic radiation with a frequency between 10^18 to 10^21 Hz, can be produced when fast-moving electrons strike a metal target
• radiation therapy: the medical use of ionizing radiation to treat disease, especially forms of cancer
• radioactive: a term used to describe substances that spontaneously emit radiation from unstable nuclei.
• gamma radiation: the highest energy form of electromagnetic radiation with frequencies above 10^19 Hz, emitted from the nuclei of radiation materials