BLOCK 6: NON-IONIZING RADIATION - Unit 2: Electromagnetic (EM) Spectrum (complete) Flashcards
The range of all possible frequencies of electromagnetic radiation.
ELECTROMAGNETIC SPECTRUM
The “electromagnetic spectrum” of an object is the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object.
EMF gets its name from the two fields: electric (E) field and magnetic (H) field. These two fields are pure energy and have _______ mass and charge.
They have NO mass and NO charge. The two fields will be at 90-degree (90°) angles from each other in the far field and will support each other.
A vector field, having defined speed and direction, described by the electrical force on a unit charge in space.
ELECTRIC (E) FIELD
A vector field describing the force experienced by magnetic objects or moving electrical charges in space.
MAGNETIC (H) FIELD
EMF radiation is produced whenever a _______________ carries a current.
CONDUCTOR
Some common sources of EMF radiation are microwave ovens, diathermy, radar, television radio communications, and microwave data link transmission.
Four equations that, together, form a complete description of the production and interrelation of electric and magnetic fields.
MAXWELL’S EQUATIONS (MAXWELL-HEAVISIDE EQUATIONS)
When these laws are used to express the fields associated with the conductor, there is an electric and magnetic component, termed the radiated field, which varies inversely with distance from the source.
The electric and magnetic fields in the immediate vicinity of an antenna that are non-propagating (do not support each other) and exist in a complex temporal and spatial pattern. These induction fields diminish in strength more rapidly than in inverse proportion to distance.
NEAR FIELD
At distances of a few wavelengths, the E and H fields pass through a transitional phase into the _______________, where power density decreases at a predictable rate vs. distance.
FAR FIELD
The amount of work that can be performed by a force, an attribute of objects and systems that is subject to a conservation law; the ability to do work.
ENERGY
The number of periods or regularly occurring events of any given kind in a unit of time, usually in one second. It is the number of cycles or completed alternations per unit time of a wave or oscillation.
FREQUENCY
The distance, measured in the direction of propagation of a wave, between two successive points in the wave that is characterized by the same phase of oscillation. Simply, it is the distance from a point on one cycle to the same point on the next cycle.
WAVELENGTH
A physical quantity describing the rate of delivery or transmission of energy.
RADIOFREQUENCY POWER
Electromagnetic radiation is emitted in the form of a __________, which has no mass and no charge but is pure energy.
PHOTON
Any process in which energy emitted by one body travels through a medium or through space, ultimately to be absorbed by another body.
RADIATION
What makes it radiation is that the energy radiates (i.e., it travels outward in straight lines in all directions) from the source.
Any type of radiation that does not carry enough energy to ionize atoms or molecules. Most especially, it refers to the lower energy forms of electromagnetic radiation (i.e. radio waves, microwaves, terahertz radiation, infrared light, and visible light).
NON-IONIZING RADIATION
The range of the EM Spectrum primarily used for communication.
RADIOFREQUENCY RANGE (RFR)
The frequency range for RFR is _____ kHz to _____ GHz.
3 kHz - 300 GHz
Also known as radiant heat, _______________ is found at the lower energy end of the visible spectrum.
INFRARED
Found at wavelengths between 400-700 nm. It is received by the eye and is interpreted as color depending on its wavelength.
VISIBLE LIGHT
Found above the visible range and bridges the gap between ionizing and non-ionizing radiation.
ULTRAVIOLET LIGHT
Long wave UV is what is typically referred to as “black light”, where short wave UV, which crosses into ionizing radiation, can be used for sanitation and water treatment.
Consists of subatomic particles or electromagnetic waves that are energetic enough to remove electrons from otherwise neutral atoms or molecules, ionizing them.
IONIZING RADIATION
Examples of ionizing particles are energetic alpha particles, beta particles, and neutrons.
The occurrence of ionization depends on the _______________ of the individual impinging particles or waves, not on their number.
ENERGY
Found at the high energy end of the electromagnetic spectrum, these are able to ionize atoms with which they interact.
X-RAY/GAMMA RADIATION
Generally, particles or photons with energies __________ only a few electron volts (eV) are ionizing.
ABOVE
“Any form of energy can be transformed into another form, but the total energy always remains the same.” refers to which principle?
CONSERVATION OF ENERGY
This principle was first postulated in the early 19th century and applies to any isolated system. Although the total energy of a system does not change with time, its value may depend on the frame of reference. For example, a seated passenger in a moving airplane has zero kinetic energy relative to the airplane but non-zero kinetic energy relative to the earth.
