sound waves

wave

-A disturbance that transfers energy from place to place
-does not carry matter through it

mechanical wave

A wave that requires a medium to travel through

medium

Material through which a wave travels

transverse wave

A wave that moves the medium perpendicular to the direction in which the wave travels

Crest

Highest point of a transverse wave

Trough

Lowest point of a transverse wave

longitudinal wave

A wave that moves the medium parallel to the direction in which the wave travels

Compression

The part of a longitudinal wave where the particles of the medium are close together.

rarefaction

The part of a longitudinal wave where the particles of the medium are far apart

sound

-A disturbance that travels through a medium as a longitudinal wave
-Begins with a vibration

factors affecting speed of sound

Stiffness, density, and temperature of the medium

faster speed of sound

solids, less density, higher temperatures

slower speed of sound

gases, more density, lower temperatures

surface wave

-combination of transverse and longitudinal waves
-travels along a surface that separates 2 media (medium)
-moves in a circular motion

rest position

Position where the wave is at rest before a disturbance

Wavelength

The distance between two corresponding parts of a wave

amplitude

the distance the medium moves from the rest position

Frequency

-The number of complete waves that pass a certain point in a given amount of time
-Measured in Hertz (Hz)

pitch

-highness or lowness of a sound
-depends on frequency

relationship between wavelength and frequency

inversely proportional

Wave speed

-the speed at which a wave travels through a medium
-varies in solids, liquids, gases

wave speed formula

-speed = wavelength • frequency
-speed = distance ÷ time

Loudness

-A physical response to the energy of sound
-Depends on the intensity of the sound wave
-More energy = more amplitude = more sound
-Less energy = less amplitude = less sound
-Measured in decibels (dB)

Doppler effect

-A change in the frequency (pitch) of a wave when the source moves in relation to the observer
-Occurs because the motion of the source causes the waves to get closer together (higher pitch) or spread out (lower pitch)

electromagnetic wave

a wave that does not require a medium to travel

field

vacuum of space

characteristics of electromagnetic waves

-main sources are the sun and human technology
-all em waves travel at the same speed (300,000 km/s)
-all em waves have the same amplitude but different wavelengths and frequencies
-waves are organized by their unique frequencies on the electromagnetic spectrum

electromagnetic spectrum

the complete range of electromagnetic waves placed in order of increasing frequency

radio waves

-Electromagnetic waves with the longest wavelengths and lowest frequencies
-Travels easily through the atmosphere and other materials

AM radio

changes amplitude to encode sound info

FM radio

changes frequency to encode sound info

television

uses AM waves for picture and FM waves for sound

radio and television

-uses radio waves to transmit information
-sends out waves that carry sound and visual information

microwaves

-Electromagnetic waves that have shorter wavelengths and higher frequencies than radio waves
-Travels easily through the atmosphere and other materials

radar

-Radio Detection and Ranging
-Detects objects by sending out microwaves and receiving the reflected waves to form a picture

cell phone

-transmits and receives microwaves
-uses overlapping networks called cells
-each cell contains a tower in the center that transmits and receives microwaves

microwave oven

-heats up food from the inside
-uses beams of microwaves to make water molecules vibrate and heat up

Infrared waves

-Electromagnetic waves that have shorter wavelengths and higher frequencies than microwaves
-associated with heat
-produced when an object radiates heat
-cannot be seen, only felt
-visible to some organisms (infrared light)

Infrared Camera

records temperature differences of objects through bands of colors (thermograph)

visible light

-electromagnetic waves that are visible to the human eye
-cones in our eyes allow us to detect these wavelengths
-only makes up a small part of the EM spectrum

ultraviolet light

-electromagnetic waves with shorter wavelengths and higher frequencies than visible light
-occurs naturally in sunlight
-is absorbed by the ozone layer
-can create skin cancer and cataracts
-is visible to some insects

X-rays

-electromagnetic waves with shorter wavelengths and higher frequencies than ultraviolet rays
-can penetrate most substances, including human tissue

gamma rays

-Electromagnetic waves with the shortest wavelengths and highest frequencies
-produced by stars and some radioactive materials on Earth
-can penetrate all human tissues
-black holes release energy in gamma ray bursts