Waves & Sound exam

________ combined electric & magnetic fields to form an electromagnetic field.

James Clerk Maxwell

The speed of the propagation of an electromagnetic disturbance is the same as _________ ___ __________.

speed of light

The speed of light is _________.

3×10^10 cm/sec

___________ showed that any time any electric current oscillates in a wire or in space, it generates an electromagnetic wave that travels outward at ________.

Maxwell; 3×10^10 cm/sec

Light is an __________ ______.

Electromagnetic wave

___________ calculated the speed of light.

Michelson

Light travels so fast, it can travel ____ times around the earth in 1 second.

7.5

The closest star __________ __________ is _________ light years away from the earth.

Alpha Cenauri; 4

__________ & ___________ argued that light travels in waves.

Hooke, Huggens

___________ postulated that light rays consist of a __________ of __________.

Newton, stream of particles

Who was correct? Hooke & Huggens or Newton?

Both

In waves, the highest place is a _____________.

Crest

In waves, the lowst place is a __________.

trough

____________ is the distance between successive disturbances of the same type (crests or troughs).

wavelength

_________ is the magnitude of a disturbance, or total displacement of a wave.

amplitude

__________ is the number of disturbances (crests or toughs) passing through a given point per unit of time.

frequency

__________ equals wavelength times frequency.

speed

The speed of light in a vacuum is always ____________.

3×10^10 cm/sec

_____________ is when 2 different waves reach a single point in space at the same time & combine.

interference

When 2 waves of the same frequency and shape meet crest to crest and trough to trough, they are said to be _________ _______________.

in phase

What scientist dealt with the wave nature of light & competed experiments on the wave nature of light?

Young

Young determined with the _________ ________ experiment, that light produces interference & thus acts like a wave.

double slit

When light shines on a slotted plate, he saw ________ bands of ________ & _________ on a screen.

alternate; light & dark

The ______________ ________ is when a ray of light initiates an electric current by the outermost electrons of a metal being dislodged by a beam of light.

photoelectric effect

A key observation of the photoelectric effect is that the kinetic energy of the emitted electrons is related to the frequency of incident of light & not to its ____________.

intensity

One can get a suntan in dim winter sunlight (contains _______ _________ _______ ________) but not get a tan while sweating all night near a hot stove ( _________ __________ __________ _________.)

high energy ultraviolet light; low energy infrared radiation

______ waves do act differently than water waves.

light

_________ postulated that light waves are emitted discontinuously in quanta.

planck

__________ are individual packets of light; can have only one of a definite setoff quantized value of energy.

Quanta

Light energy is quantized & available only in discreet packets: the smallest packet is a _________.

photon

The energy of a photon is proportional to the ________ of the radiation; this became the basis for the ________ ________ ________.

frequency; modern Quantum theory

An electron will become ___________ or leave an atom only if it recieves enough energy all at once to jump from one energy level to the next or out into space.

excited

The electron gains energy equal to the photon absorbed. This is an _________ ________. An excited electron _______ this photon when it falls back to a lower level.

excited electron; emits

Who is responsible for the postulate that all matter exhibits wave behavior?

lorenz

___________ is when an electromagnetic wave bounces back from an object.

reflected

_________ objects don’t allow light to pass through them; they reflect the light.

Opaque

__________ objects allow light to pass through them; they don’t reflect the light; but _______ light through them.

transparent; transmit

___________ is the bending of light caused by changing from one medium to another (causes change in ____________).

refraction; velocity

Give 3 example of refraction:

pencil in a glass, magnifying glass in focusing the sun’s rays,mirages in the desert

______________ is whenever a charged particle accelerates & an electromagnetic wave is emitted.

emission

The __________ __________ __________ is when the electron is in its lowest energy level.

ground energy state

__________ _______________ is when the electron is in its highest energy level.

excited state

Low energy waves: electromagnetic waves from an _________ _________ have little influence or effect on the environment; barely detectable.

electric wire

____________ __________ are detectable with the use of good equipment.

radio waves

___________ transmits ___________ then searches for reflected radiation. ___________ ____________ are used for detection of these waves. The largest of these is located in the ___________.

radar; microwave; radio telescopes; Philippines

____________ waves are associated with heat.

infrared

Name a “natural IR” sensor __________; are able to “see” warm blooded animals

snakes

Men use artificial IR sensors to find __________ ____________.

diseased trees

When visible light is passed through prism & is broken into its component parts, you see a _____________.

spectrum

List the colors on the light spectrum from low frequency, long wavelenght radiation to high frequency, short wavelength radiation: _________, ___________, __________, ___________, _________, __________.

red, orange, yellow, green, blue, violet

___________ light is refracted the most & ________ the least in a prism.

violet; red

Why is the sky blue?

tiny particles scatter light, the angle of the scattering of the light gives us the blue sensation

___________ reflects all incident light.

white

_______ absorbs all incident light & converts light energy to heat energy.

black

_________ _________ gives us a suntan; may be harmful to the DNA molecule.

ultraviolet light

________ is the protection layer of the atmosphere.

ozone

____________ are produced by boiling electrons off a metal electrode & accelerating them through a potential of 100,000 volts onto a positive plate. These electrons transfer their energy to the positie plate which emits the rays.

X-rays

__________ have great penetrating power; are used to photograph bones.

X-rays

_________ are used industrially to search for flaws in welds & metal castings.

X-rays

______________ have a greater effect on living tissue than UV light; are more penetrating.

X-rays

___________ __________ are protons emitted by nuclear transformations.

gamma rays

__________________ are produced using a focusing device to concentrate lots of electromagnetic energy on an extremely small area; generates light that does not spread out, but maintains a narrow beam producing a coherent, ordered, nonchaotic light.

lasers

List 5 uses for lasers:

melt holes in small jewels, computer technology to burn microscopic holes in computer tape, global surveying, used by surgeons to weld displaced retina back into position without disturbing the rest of the eye, 3D photographs

_____________ ____________ are used for cutting cloth.

pencil lasers

List the 2 types of waves:

transverse waves & longitudinal waves

List the characteristics of transverse waves:

are electromagnetic waves; have crests & troughs; will travel in a vacuum; wave propagation is perpendicular to wave velocity

List the characterisitcs of longitudinal waves:

sound waves/elastic waves; like action in a coiled spring; will not travel in a vacuum; wave propagation & wave velocity are in the same direction; travel faster in denser medium

Give 2 functions of ears:

as a range & direction finder; helps people balance

________ name for the outer ear; functions in funneling sound waves to the external ear.

auricle or pinna

The ______ ______ is the inside end of the external ear canal.

ear drum

The __________ form a mechanical bridge between the inner ear & the ear drum.

ossicles

Of the ossicle bones this is the hammer: _________.

malleus

Of the ossicle bones, this is the anvil: ___________.

incus

Of the ossicble bones, this is the stirrup: __________.

stapes

List the functions of the inner ear:

to convert sound induced mechanical waves to nerve impulses; aid in maintaining balance & spatial orientation

The ___________ is responsible for the conversion of sound induced mechanical vibrations into nerve impulses & contains fluid.

cochlea

The ________ of _________ has thousands of tiny hairs that convert vibrations into nerve impulses.

organ of Corti

The _________ _______ connects the organ of Corti to the brain.

auditory nerve

_________ ____________ are sounds in which compressions & rarifications of air alternated sinusoidally (like a sine wave).

pure sounds

T or F: There are many natural sounds that are pure tones.

false

Musical sounds are classified as to ________ ________ or _________.

quality, depth, or richness

The _______ ________ of one note on different instruments in the same but the _____ cause a different sound.

fundamental frequency; overtones

__________ erratic intermittent or statistically random oscillations.

noise

____________ is the unit used by physicists for measuring loudness.

Bel

The unit used by physicists for measuring loudness is named after __________.

Alexander Graham Bell

A _________ defines a ten fold increase in intensity.

Bel

A _____ is 1/10 of a Bel.

decibel

The sensitivity of the human ear depends upon the __________ of the sound to which you are exposed.

frequency

The human ear is most sensitive to pure tones at about _________ Hz.

4,000

________ ___________ is sound below 50 Hz; human ears can’t hear these.

infrasound

____________ are sounds above 15,000 Hz.

ultrasounds

Ultrasounds are used for (name 5 uses):

in industry for welding, cutting, drilling & cleaning; used in medical diagnosis

Give a place or source of sound that the sound level is: Quiet _______; Very loud _______; Painfully loud (can cause immediate permanent damage) ___________, _________, __________.

QUIET - library or average bedroom; VERY LOUD - diesel truck, food blender; PAINFULLY LOUD - max recorder rock music, jet plane at take-off, rocket engine

List 2 effects of noise:

Interferes with communication; diminishes hearing; affects our health & behavior

Efficiency goes ________ when _________ goes up.

down; noise

List 3 ways to control noise:

reduce the source - reduce sound power; interrupt the path - use sound absorbing media; protect the receiver

List 3 ways to protect the receiver:

naturally (put your hands over your ears), ear plugs, ear muffs

_______ speed is speed slower than the speed of sound.

subsonic

________ speed that is the same as the speed of sound.

sonic

__________ speeds greater than the speed of sound.

supersonic