NEETS MOD 10

Which Term means "movement through a medium"

Propagation

What can be defined as a disturbance (sound, light, radio waves) that moves through a medium (air, water, vacuum)

Wave

What can be defined as a recurring disturbance advancing through space with or without the use of a physical medium?

Wave motion

Which type of waves are water waves known as because the motion of the water is up and down, or at right angles to the direction in which the waves are traveling?

Transverse

Which type of waves are waves in which the disturbance takes place in the direction of propagation?

Longitudinal

What is the vehicle through which the wave travels from one point to the next?

Medium

What is the position call that a particle of matter would have if it were not disturbed by wave motion?

Reference line

What is the distance in space occupied by one cycle of a radio wave at any given instant?

Wavelength

What unit of measurement are wavelength expressed in?

Meters

Which wave property gives a relative indication of the amount of energy the wave transmits?

Amplitude

What is a continuous series of waves called having the same amplitude and wavelength?

Wave train

The number of vibrations, or cycle, of a wave train in a unit of time it's called the frequency of the wave train and is measured in what?

Hertz

Which term refers to the number of occurrences that take place in one second?

Hertz

Which propagation property is the rate at which the disturbance travels through the medium, or the velocity with which the crest of the wave moves along?

Velocity

What is the time in which one complete vibratory cycle of events occurs?

Period

What is a wave called that is directed toward the surface of the mirror?

Incident

What is the angle between the reflected wave and the normal called?

Angle of reflection

Which law states that the angle of incidence is equal to the angle of reflection?

Law of reflection

What is the bending of the wave path when the waves made an obstruction?

Diffraction

What is the apparent change in frequency or pitch when a sound source moves either toward or away from the listener, or when the listener moves either toward or away from the sound source?

Doppler affect

How does sound travels through a medium?

Wave motion

In the study of physics, what is defined as a range of compression wave frequencies to which the human ear is sensitive?

Sound

Which type of sounds are capable of being heard by the human ear?

Sonics

The Navy has set an arbitrary upper limit for sonics at 10,000 Hz and a lower limit at what?

15 Hz

What is it standard practice to refer to sound above 10,000 Hz ass?

Ultrasonic

What are sounds below 15 Hz known as?

Infrasonic

How many basic elements for transmission and reception of sound must be present before a sound can be produced?

3

Which two general groups may sounds be broadly classified into?

Noise or tones

Sound has three basic characteristics: pitch, intensity, and what else?

Quality

Which term is used to describe the frequency of a sound?

Pitch

What is a measure of the sound energy of a wave?

Intensity

What is the sensation the intensity (and sometimes frequencies) the sound wave produces on the ear?

Loudness

What are the two basic physical properties that govern the velocity of sound through the medium?

Elasticity and density

What is the ability of a strained body to recover it shape after D formation?

Elasticity

What property of a medium or substance is the mass per unit volume of the medium or substance?

Density

What is the velocity in FPS that sound will travel through air at 32°F?

1,087

What is the science of sound referred to as?

Acoustics

What is the reflection of the original soundwave as it bounces off a distant surface called?

Echo

An empty rooms or other confined spaces sound may be reflected several times to cause what is known as what?

Reverberation

What is any disturbance, man-made or natural, that causes an undesirable response or the degradation

of a wave referred to as?

Interference

What is the most complex sound wave that can be produced?

Noise

What is light a form of?

Electromagnetic radiation

Current like theory says that light is made up a very small packets of electromagnetic energy called what?

Photons

Approximately how many miles per second does light travel?

186,000

What is the large volume of like called?

Beam

What is the narrow volume of light called?

Pencil

Which type of substance is one through which you can see clearly?

Transparent

What are substances called in which some light rays can pass through but objects cannot be seen clearly because the rays are diffused?

Translucent

Which year did Ole Roemer discover that light travels approximately 186,000 miles per second in space?

1675

How many times in one second candle light beam circle the earth?

7.5

Which term is used to designate the entire range of electromagnetic waves arranged in order of their frequencies?

Spectrum

What is a conductor or a set of conductors used either to radiate electromagnetic energy into space or to collect this energy from space?

Antenna

Which two primary components does an electromagnetic wave consist of?

Electric and magnetic field

What is the smallest unit of radiant energy that makes up light waves in radio waves?

Photon

Which units are used for measuring the wavelength of light?

Angstrom

What are the primary colors of light?

Red green and blue

What are the complementary colors of light?

Magenta, yellow, and cyan

Which two basic fields are associated with every antenna?

Induction and radiation

Which field is associated with the energy stored in the antenna?

Induction

Which type of antenna has an electrical length equal to half the wavelength of the signal being transmitted?

Half wave

What is an energy wave called that is generated by transmitter?

Radio wave

What is the basic shape of the waves generated by transmitter?

Sine wave

What is the number of cycles of a sine wave that are completed in one second known as?

Frequency

The frequencies falling between 3 kHz and what are called radio frequencies since they are commonly used in radio communications?

300 GHz

The usable radio frequency range is roughly 10 kHz to what?

100 GHz

What is the very low frequency (VLF) range?

3 to 30 KHz

What is the LF frequency range?

30 to 300 kHz

What is the medium frequency MF frequency range?

300 to 3000 kHz

What is the high frequency HF frequency range?

3 to 30 MHz

What is the very high frequency (VHF) frequency range?

30 to 300 MHz

What is the ultrahigh frequency (UHF) frequency range?

300 to 3000 MHz

What is the super high frequency (SHF) frequency range?

3 to 30 GHz

What is the extremely high frequency (EHF) frequency range?

30 to 300 GHz

Any frequency that is a whole number multiple of a smaller basic frequency is known as what property of that basic frequency?

Harmonic

What is the property of a radio wave which is simply the amount of time required for the completion of one full cycle?

Period

What is the space called occupied but one full cycle of radiowave at any given instant?

Wavelength

The velocity (or speed) of a radio wave radiated into free Space by a transmitting antenna is equal to the speed of light which is how many miles per second?

186,000

Where Must the receiving antenna be located for maximum absorption of energy from the electromagnetic fields?

Plane polarization

Troposphere, stratosphere, along with what else are the three separate regions, or layers that the earth atmosphere is divided into?

Ionosphere

The troposphere is the portion of the earths atmosphere that extends from the surface of the earth to the height of about 3.7 miles at the north pole or the south pole and how many miles at the equator?

11.2

Which atmosphere layer has relatively little effect on radio waves because it is a relatively calm region with little or no temperature changes?

Stratosphere

The ionosphere extends upward from about 31.1 miles to a height of about how many miles?

250

What is the most important region of the atmosphere for long distance point to point communications?

Ionosphere

What are the two principal ways in which electromagnetic (radio) energy travels from a transmitting antenna to a receiving antenna?

Ground and sky waves

The surface wave is impractical for long distance transmissions at frequencies above what frequency?

2 MHz

Which frequency band is used for sky wave propagation?

HF

What is the process known as of upsetting electrical neutrality?

Ionization

What occurs when the free electrons and positive ions collide with each other?

Recombination

How many layers is the ionosphere composed of?

3

Each ionosphere layer has a maximum frequency at which radio waves can be transmitted vertically and refracted back to earth which is known as what?

Critical frequency

What is the distance from the transmitter to the point where the skyway is first return to earth?

Skip distance

What is the zone of silence between the point where the groundwave becomes too weak for reception in the point where the skyway is first return to earth?

Skip zone

What results in the loss of energy of a radio wave and has a pronounced affect on both the strength of received signals and the ability to communicate over long distances?

Absorption

Fading on ionospheric circuits is mainly a result of what?

Multipath propagation

And what practice are two transmitters into receivers used, each pair tune to a different frequency, with the same information being transmitted simultaneously over both frequencies?

Frequency diversity

When a wide band of frequencies is transmitted simultaneously, each frequency will vary in the amount of fading. What is this variation called?

Selective fading

The combined effects of absorption, ground reflection loss, and what else account for most of the energy losses of radio transmissions propagated by the ionosphere?

Free space loss

There is little natural interference above what frequency?

30 MHz

How many mean classes can the regular variations that affect the extent of ionization in the ionosphere be divided into?

Four

What are responsible for variations in the ionization level of the ionosphere?

Sunspots