Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
141 Cards in this Set
- Front
- Back
- 3rd side (hint)
|
What is Electricity? |
the flow of electric charge. |
The flow of.. |
|
|
What is Electric Charge? |
a property of some subatomic particles, which determines their electromagnetic interactions. |
|
|
|
What is Electronic Current? |
a movement or flow of electrically charged particles. |
|
|
|
What is Electric Field of Force? |
The space between and around charged bodies in which their influence is felt. |
|
|
|
What is Electric Potential? |
the capacity of an electric field to do work on an electric charge. |
|
|
|
What is Coulomb's Law of Charges? |
CHARGED BODIES ATTRACT OR REPEL EACH OTHER WITH A FORCE THAT IS DIRECTLY PROPORTIONAL TO THE PRODUCT OF THEIR INDIVIDUAL CHARGES, AND IS INVERSELY PROPORTIONAL TO THE SQUARE OF THE DISTANCE BETWEEN THEM. |
|
|
|
What are other names used to refer to as Electric fields of force? |
ELECTROSTATIC FIELDS and DIELECTRIC FIELDS |
|
|
|
What are the three main sub-atomic particles of the atom called? |
Proton,neutron and electron |
|
|
|
What is Voltage? |
Electric potential or the measurement of how much work an electric field can do. |
|
|
|
What is Energy? |
The ability to do work |
|
|
|
What is Electric power? |
The rate at which electric energy is converted to or from another energy form |
|
|
|
What are the 6 ways to produce voltage? |
-Friction -Pressure -Heat -Light -Chemical -Magnetism |
|
|
|
Voltage produced by light is also called? |
PHOTOELECTRIC VOLTAGE. |
|
|
|
What is a Series Circuit? |
One path to follow |
|
|
|
What is a Parallel Circuit? |
Multiple paths to follow |
|
|
|
What is Direct Current (DC)? |
Current flows in one direction. |
|
|
|
What is Alternating Current? |
Current alternates direction. |
|
|
|
What is an Open Circuit? |
A break exists preventing current flow. |
|
|
|
What is a Closed Circuit? |
Current is free to flow through a circuit. |
|
|
|
What is a Short Circuit? |
Very little to no resistance exists in a circuit |
|
|
|
What does AMPERES measure? |
The Electric Current |
|
|
|
What is Resistance Measured in? |
Ohms(R) |
|
|
|
What are Resistors? |
components manufactured to possess specific values of resistance. |
|
|
|
What is a Schematic Diagram? |
The schematic diagram is a "picture" of the circuit that uses symbols to represent the various circuit components |
|
|
|
What does Watts (P) measure? |
Electric Power |
|
|
|
What is Ohms Law? |
The current in a circuit is DIRECTLY proportional to the applied voltage and INVERSELY proportional to the circuit resistance. |
|
|
|
What are the three fundamental conditions that must exist before a voltage can be produced by magnetism? |
-There must be a CONDUCTOR -There must be a MAGNETIC FIELD -There must be RELATIVE MOTION |
|
|
|
What is Voltage measured in? |
Volts (E) |
|
|
|
What is Current measured in? |
Amps (I) |
|
|
|
What is Power measured in? |
Watts (P) |
|
|
|
What is Matter? |
Anything that occupies space and has weight. |
|
|
|
What does matter normally exist in? |
solid,a liquid, a gas or plasma. |
|
|
|
What is an Element? |
A Substance which cannot be reduced to a simpler substance by chemical means. |
|
|
|
What is a Compound? |
a chemical combination of elements which can be separated by chemical means, but not by physical means |
|
|
|
What is a Mixture? |
Combination of elements or compounds that can be separated by physical means. |
|
|
|
What is an Atom? |
Is the smallest particle of an element. |
|
|
|
What is a Molecule? |
Is the chemical combination of two or more atoms. |
|
|
|
What is a Conductor? |
Elements that transfer electrons very readily |
|
|
|
What is an Insulator? |
extremely high resistance to the flow ofelectricity |
|
|
|
What is a Semiconductor? |
All matter between these two extremes. |
|
|
|
The lowest point of a wave? |
Trough |
|
|
|
What is attenuation of a wavelength? |
Loss of power over distance. |
|
|
|
What is a wavelength? |
The distance that it takes for one complete sine wave. |
|
|
|
Frequency |
How often a complete wave occurs within a given time period. |
|
|
|
What frequency unit is necessary to produce meters in a wavelength calculation with no conversions? (Specifically for this class) |
Megahertz |
|
|
|
What is the base unit for measuring frequency? |
Hz |
|
|
|
What is the base unit for time? |
Seconds |
|
|
|
What is the base unit for distance? |
Meters |
|
|
|
What type of waves are Radio Waves? |
Electromagnetic Waves |
|
|
|
What is the E-Field? |
Electric Field |
|
|
|
What is the H-Field? |
Magnetic Field |
|
|
|
What are the E and H Fields collectively known as? |
Radiation Fields |
|
|
|
A charged capacitor stores energy in the form of an? |
Electric Field |
|
|
|
What does half wave antenna mean? |
the electrical length equal to half the wavelength of the signal being transmitted. |
|
|
|
How is a magnetic field formed? |
A current flowing through a conductor |
|
|
|
What wave is arranged at right angles of each other and what components. |
The Electromagnetic Wave and the E-Field is a right angle to the H-Field |
|
|
|
What kind of current is required to create radio waves? |
Alternating Current (AC) |
|
|
|
What is Frequency? |
The number of waves that pass a fixed place in a given amount of time (1 Second). |
|
|
|
What is Amplitude? |
Height of a sine wave |
|
|
|
What is Peak Amplitude? |
Measured from the reference line to the top of the peak or the bottom of the trough. |
|
|
|
What is Peak-to-Peak Amplitude? |
Measured between the maximum positive and negative values. |
|
|
|
What is Period? |
The period, or "length", of a wave determines the time to complete one cycle. |
|
|
|
What is Cycle? |
The cycle of a sine wave is the completion, from any given point on a wave to the same point on the next wave. |
|
|
|
Frequency and Wavelength are what? |
Inversely Proportional |
|
|
|
What is Polarization? |
direction of the lines of force making up the electric field. |
|
|
|
If the line of electric force are perpendicular the wave is what? |
the wave is vertically polarized. |
|
|
|
If the line of electric force are parallel the wave is what? |
the wave is horizontally polarized. |
|
|
|
What is Circular Polarization? |
a wave whose plane of polarization rotates through 360° as it progresses forward. |
|
|
|
What is a Direction Antenna used for? |
to propagate radio waves in a specific direction |
|
|
|
What is an Omni-Directional Antenna used for? |
used to propagate radio waves in “all” directions |
|
|
|
What does an Omni-Directional Antenna create near it? |
Cone of Silence |
|
|
|
What is the Velocity of a wave? |
Speed of light |
|
|
|
What does Reciprocity state? |
anantenna works the same for transmitting or for receiving |
|
|
|
Which field determines the polarization of an electromagnetic wave? |
E-field |
|
|
|
Name the types of polarization for radio waves. |
Horizontal, vertical, circular |
|
|
|
What is Propagation? |
Movement through a medium |
|
|
|
A wave is defined as what when moving through a medium? |
Distubance |
|
|
|
What is a Medium? |
Air, Water, Space (Vacuum), Wire |
|
|
|
What is a Lambda? |
Scientific term for wavelength |
|
|
|
What does Transverse mean? |
Up and Down motion of the wave or atright angles to the direction in which the waves are traveling |
|
|
|
What is the Up and Down motion of a wave called? |
Transverse |
|
|
|
What are sound waves called? |
LONGITUDINAL WAVES |
|
|
|
What are LONGITUDINAL WAVES also called? |
Compression Waves |
|
|
|
What does Rarefied mean? |
made less dense or expanded |
|
|
|
The object producing the waves is called the what? |
Source |
|
|
|
Objects responding to the wave is called the? |
Detector or Reciever |
|
|
|
What wave does not require a medium? |
Electromagnetic Wave |
|
|
|
Sound waves travel at the speed of what? |
Sound |
|
|
|
What is a Transmitter? |
Electronic Device that generates(RF) energy |
|
|
|
What is a Antenna? |
Converts energy into radio waves |
|
|
|
What is a Receiver? |
Converts Radio waves into energy |
|
|
|
What converts energy into radio waves? |
Antenna's |
|
|
|
What converts radio waves into energy? |
Reciever's |
|
|
|
What is Reflection? |
when a wave strikes an object and the wave “bounces off” or changes direction |
|
|
|
What is Refraction? |
the bending of a wave as it enters a new medium. |
|
|
|
The bending of a wave is always towards what? |
the medium that has the lower velocity of propagation. |
|
|
|
What is Diffraction? |
natural tendency to bend around the obstacle. |
|
|
|
What are the layers that make up the atmosphere? |
-Troposphere -Stratosphere -Ionosphere -Free Space |
|
|
|
What is the Troposphere? |
where most weather effects occur |
|
|
|
What is the Stratosphere? |
located between Troposphere andIonosphere and has very little effect on radio waves |
|
|
|
What is the Ionosphere? |
partof the atmosphere that is ionized by solar radiation and contains layers ofelectrically charged ions |
|
|
|
What is Free Space? |
Area of atmosphere where the particles are so far apart they rarely ever collide. (Nearly a vacuum) |
|
|
|
What are the four layers in the ionosphere? |
D, E, F1, F2 |
|
|
|
What happens to the Ionosphere layers at night? |
-D disappears -E Fades -F1 and F2 combine |
|
|
|
What are the two principle RF transmitting methods? |
Sky waves and Ground Waves |
|
|
|
What are the three component ground waves? |
-Surface Wave -Space Wave -Ground Reflected Wave |
|
|
|
What wave travels along the earths surface? |
Surface Wave |
|
|
|
What does a Surface Wave do? |
Travel along the earths surface |
|
|
|
What is LOS Propagation? |
Anything getting in the way of the radio waves. (Hills, Mountains, Buildings) |
|
|
|
Sky waves are what? |
Radiated upward and returned toEarth |
|
|
|
What type of ground wave goes directly from antenna to antenna? |
Space Wave or Direct Wave |
|
|
|
What does a Space wave do? |
Goes directly from antenna to antenna |
|
|
|
What does the the sun do to the Ionosphere? |
Ionization |
|
|
|
Refraction depends on what? |
-Density -Frequency -Angle |
|
|
|
Higher Density in the Ionosphere results in what? |
refract the wave quicker |
|
|
|
What is Critical Frequency? |
Max frequency wave is refracted back to earth |
|
|
|
What is the Max frequency wave is refracted back to earth called? |
Critical Frequency |
|
|
|
What is a Critical Angle? |
When the wave is reduced to an angle that is less than vertical it strikesthe layer and is refracted back to Earth |
|
|
|
When a wave is reduced to an angle that is less than vertical it is called what? |
Critical Angle |
|
|
|
What is the Skip Zone? |
a zone of silence between the point where the ground wave becomes too weak forreception and the point where the sky wave is first returned to Earth |
|
|
|
What is NVIS |
Near Vertical Incident Sky Waves |
|
|
|
Because of NVIS there is no what? |
Skip Zones |
|
|
|
What are the four regular Ionosphere Variations? |
-Daily (Day and Night) -Seasonal -11 year sun spot cycle -27 day sun spot cycle |
|
|
|
Irregularly dark areas on the sun are called? |
Sunspots |
|
|
|
What are the three Irregular Ionosphere Variations? |
-Sporadic E -Sudden Ionosphere Disturbances -Ionospheric Storm |
|
|
|
What is an Ionosphere Storm? |
Disturbances in the Earth’smagnetic field |
|
|
|
What is Sporadic E |
Cloud-like patches of high ionization |
|
|
|
What disturbance occurs without warning? |
Sudden Ionosphere Disturbance |
|
|
|
What is wave Degradation? |
anything that causes a signal loss |
|
|
|
What are 4 types of Degradation? |
-Absorption -Fading -Transmission Loss -Electromagnetic Interference (EMI) |
|
|
|
Absorption has the greatest what? |
Adverse effect on radio waves |
|
|
|
Multi-path fading is minimized by? |
Space Diversity and Frequency Diversity |
|
|
|
What are three factors that can cause fading? |
Polarization changes from ionosphere, Ionosphere absorption, multipath fading |
|
|
|
What is Temperature Inversion (Ducting) ? |
When layers of warm air form above layers of cold air |
|
|
|
What is Tropospheric Scattering? |
Whena radio wave passing through the troposphere meets a turbulence, it makes anabrupt change in velocity |
|
|
|
Howdoes rain affect radio wave transmissions? |
They are attenuated by absorptionand scattering. |
|
|
|
Whatare 2 ways that a line-of-sight signal can be transmitted beyond line-of-sight? |
Tropospheric Scattering, andAtmospheric Ducting. |
|
|
|
What is an Electric field?
|
the electric force per unit charge
|
|
|
|
What is a decibel (dB)?
|
a logarithmic unit that expresses the ratio of two values of a physical quantity, often power or intensity
|
|
|
|
what is Polarization?
|
a property of waves that can oscillate with more than one orientation
|
|
|
|
What is propagation?
|
the movement through a median
|
|
