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76 Cards in this Set
- Front
- Back
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What is propogation?
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Movement through a medium
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Define Wave
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A disturbance that moves through a medium
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Define wave motion.
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1.A reoccuring disturbance advancing through space. 2. Energy moving/transferring from one point to another.
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What are traverse waves?
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Traverse waves travel at right angles to te direction of propogation. (light, heat , radio)
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What are longitudinal waves?
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Longitudinal waves are waves in which the disturbance takes place in the direction of propagation.
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List Formulas: velocity, frequency,time, wavelength
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V = f x wavelength
T (1 vibration)=1/f f = 1/ T Wavelength= v/f |
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What is the law of reflection?
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The angle of incidence is equal to the angle of reflection.
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List frequency ranges for light spectrum. red, orange, yellow, green, blue green, blue, indigo, violet
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Red = 650-800
Orange = 600- 650 Yellow = 580-600 green = 520- 580 Green blue = 500-520 Blue = 470-500 Indigo = 440-470 violet = 400-440 |
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State the frequency range for VLF waves.
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3Hz - 30 Hz
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State the frequency range for LF waves.
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30Hz - 300Hz
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State the frequency range for MF waves.
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300 Hz - 3 MHz
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State the frequency range for HF waves.
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3 MHz - 30 MHz
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State the frequency range for VHF waves.
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30 MHz - 300 MHz
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State the frequency range for UHF waves.
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300 MHz - 3 GHz
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State the frequency range for SHF waves
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3 GHz- 30 GHz
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State the frequency range for EHF.
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30 GHz- 300 GHz
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What is the major advantage of the telegraph over earlier mentods of communiction?
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Range
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Radio waves trave at what speed?
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Speed of light
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Which type of energy cannot be seen, heard, or felt?
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Radio waves
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What is the wave law of reflection?
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The angle of incidence is equal to the angle of reflection.
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What is the vehicle through which a wave travels from point to point?
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Medium
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The reception of an AM-band radio signal over mountains can be explained by which of the following principles of wave propagation?
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Diffraction
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What wave propagatiion principle accounts for the alleged increase in frequency ans a train whistle approaches and the alleged decrease in frequency as it moves away?
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Doppler Effect
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Longitudinal wave disturbances that travel through a medium are known as what type of waves?
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Sound
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Varying which of the following wavve characteristics will cause the length of sound waves to vary?
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Frequency
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What are the 3 basic characteristics of sound?
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Pitch intensity and quality
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In sound terms, what is the same as a wave reflection?
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Echo
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Multiple reflections of sound waves are
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Reverberation
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A cavity that vibrates at its own natural frequency and makes a sound louder than other frequencies demonstrates what sound wave term?
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Resonance
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The scientist, J.C. Maxwell, developed the theory that small packets of electromagnetic energy called photons produce:
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Light
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Define light beam
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A large volume of light radiating in a fiven direction
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What are the primary colors of light
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RGB redgreen blue
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What are the secondary colors of light
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Magenta yellow and cyan
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What causes sunlight to separate ino different wavelengths and display a rainbow of colors when passed thru a prism?
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Dispersion
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The sun, gas flames, and electric light filaments are visible because they are
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Self luminous
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Define translucence
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Substance are able to transmit light waves but objects cannot be seen through them.
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Define transparence
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Substances that transmit almost all of the light waves falling upon them
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the electromagnetic range arranges waves in order of its
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frequency
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what type of wave has the highest frequency?
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X Ray
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What device is used to radiate and or collect electromagnetic waves
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Antenna
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The electromagnetic field is comprised of
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Electric field and magnetic field
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The magnetic field radiated from an antenna is produced by what
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Electrical Current
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The Electric field radiated from an antenna is produced by what property?
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Electrical voltage
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Applying rf energy to the elements of an antenna results in what relationship between voltage and current?
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Rhase relationship where voltage lags current by 90 degres
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What field exists close to the conductor of an antenna?
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THE iNDUCTION FIELD it also carries a current
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What field travels through space after being detached from the current-carrying rod of an antenna?
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Radiation
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When do electric and magnetic fields on an antenna reach their maximum intensity?
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When they are a quarter-cycle apart
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When do electric and magnetic fields on an antenna reach their maximum intensity?
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When they are a quarter-cycle apart
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What is input impedence?
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A measure of the voltage to current ration (Ein/I in) at the input end of a transmission line
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What is input impedence?
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A measure of the voltage to current ration (Ein/I in) at the input end of a transmission line
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Name an advantage of a shielded pair transmission line
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Uniform capacitance (no loss) throughout the line
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Name an advantage of a shielded pair transmission line
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Uniform capacitance (no loss) throughout the line
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What is the #1 advanage of coaxial cable lines?
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Low radiation losses
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What is the #1 advanage of coaxial cable lines?
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Low radiation losses
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Define radiatiON
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When transmission line loss is caused by magnetic line of force not returning to the conductor
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Define radiatiON
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When transmission line loss is caused by magnetic line of force not returning to the conductor
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What is the standard characteristic impedance of a transmission line
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50-600 ohms
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What is the standard characteristic impedance of a transmission line
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50-600 ohms
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Define incident waves
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The initial waves that travel from the source to the load of a transmission line
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Define incident waves
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The initial waves that travel from the source to the load of a transmission line
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Define reflected waves
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Waves that travel from the output end to the input end of a transmission line
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Define reflected waves
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Waves that travel from the output end to the input end of a transmission line
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What characteristics control the velocity of propagation?
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Capacitance and inductance
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What characteristics control the velocity of propagation?
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Capacitance and inductance
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Current X voltage =
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he total charge on a transmission line
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Current X voltage =
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he total charge on a transmission line
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What is the total # of moving waves in an AC signal
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2
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What is the general maximum distance for Line Of Sight Communications?
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25 miles
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Transmission of informatiion to a satellite is don on what frequency?
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UP-Link
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An earth terminal receives signals on what frequency?
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DOwnlink
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Define perigree
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THe part of a satellite's orbit closest to the earth
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In a LOS communication system, propagatiion is affected bywhich of the following layers of the atmosphere?
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Troposphere upto 16 Km
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Radio waves refract off of what atmosheric layer?
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Ionosphere
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Airplanes fly in this layer of the atmoshpere.
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Stratosphere also contains our O zone layer Upto 50 Km
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Discuss the mesosphere.
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Too high for aircraft 80 Km, too low for satellites, meteors burn up here
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Dicscuss thermosphere
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500-1,000 Km above the earth, contains ionosphere where satellites orbit, solar flares and gravity affects the radio wave because many wave atoms have lost electrons causing them to be charged ions influenced by these things
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