Chapter 9 Test Flashcards
What causes waves?
something that vibrates
waves ____ energy
carry
transmit
waves carry ___ but not ___
energy
the matter with the wave
what are the 2 types of waves
compressional
transverse
do all waves need a medium to transfer energy
no
what is the main example of a longitudinal/compressional wave
sound wave
examples of transverse waves
water, radio, micro, infrared, light, uv, x, gamma
what happens in reflection?
wave strikes an object then the wave bounces off the object
What types of waves can be reflected?
all
What must happen in order to see reflection?
light waves must reflect off an object and those waves must enter your eye
What is the reflection of sound waves called?
echoes
what is the law of reflection
angle of incidence = angle of reflection
When does a wave bend?
refraction and defraction
what happens in refraction? why?
the wave bends
because of a change in the waves speed when it goes from one type of medium to another at an angle
___ waves can be refracted
all
the ___ the rate of speed change of the wave, the ___ the wave refracts
greater
more
when a wave enters a medium and slows down, the wave will refract ___ the normal line
toward
when a wave enters a medium and the wave goes faster, the wave will refract ___ the normal line
away from
what happens in diffraction
a wave bends around a barrier or through an opening
___ waves can be diffracted
all
short wavelengths diffract ___
less
long wavelengths diffract ___
more
the amount of diffraction depends on…
the size of a waves wavelengths
the size of the barrier or opening the wave encounters
sound waves have ___ wavelengths
long
light waves have ___ wavelengths
short
AM radio waves have ___ wavelengths
longer
FM radio waves have ___ wavelengths
shorter
What happens in wave interference
two or more waves overlap and combine to form a new wave
Can two waves be in the exact same place at the same time? Why or why not?
yes because they are energy not matter - this is what causes the interference
What are the two types of interference
constructive
destructive
what is constructive interference?
when crests and troughs of two or more waves meet and combine forming a new wave
what is destructive interference?
the crests and troughs of two or more waves meet oppositely of one another and cancel out part or all of the waves forming a new wave
short wavelengths refract ___
more
long wavelengths refract ___
less
___ diffraction occurs if the wavelength is smaller than the object
less
___ diffraction occurs if the wavelength is the same size as the object
more
the amount of diffraction that occurs depends on…
how big the obstacle or opening is compared to the wavelength
why can you hear the soundwaves from a classroom while down the hall but not see the lightwaves
the wavelengths of soundwaves are similar in size to a door opening
sound waves diffract around the door and spread out the hallway
light waves have a much shorter wavelength
they are hardly diffracted at all by the door
__ radio reception is often better than __ reception around tall buildings and natural barriers such as hills
AM
FM
What is natural frequency?
the frequency at which a material vibrates
What three factors affect an object’s natural frequency?
size
shape
type of material the object is made of
what is resonance
the process where an object vibrates because it absorbs the energy of another wave at the object’s natural frequency
What is the wave velocity formula
v = λ x f
What is the unit for velocity
m/s
What is the unit for frequency
hertz (Hz)
What is the unit for wavelength
m
What is the unit for the period of the wave
s
what are seismic waves
waves inside earth that cause the crust to move, bend, or break
___ waves can be longitudinal or transverse
water, seismic
where can seismic waves travel
through earth or along earth’s surface
how can waves differ
how much energy they can carry
how fast they travel
what do the properties of a wave depend on
the vibrations of the wave source
the material in which the wave travels
What do wave properties affect
how we see objects or hear sounds
do all waves have wavelengths
yes
what is a wavelength
the distance between one point on a wave and the nearest point just like it
what is the symbol for wavelength
the greek letter lambda: λ
what are you doing when you tune a radio to a certain station
choosing radio waves of a certain frequency
what is frequency
the number of wavelengths that pass a fixed point each second
(the number of times that a point on a wave moves up or down/ back and forth each second)
1Hz = __
1/s
what is period
the amount of time it takes one wavelength to pass a fixed point
frequency and period are always ___
inversely proportional
when a waves frequency increases the period of the wave ___
decreases
if frequency increases the wavelength will ___
decrease
which waves travel faster: light or sound
light
What does the speed of a wave depend on
the type of medium the wave is traveling through
sound waves travel fastest in ___, slowest in ___
solids
gases
sound tends to go faster in a medium at a ___ temperature
higher
Light waves travel fastest in ___ and slowest in ____
vacuum
solids
what is the unit for wave speed
m/s
the greater the amplitude of a wave, the ___ energy the wave will carry
more
the amplitude of a wave measures the…
size of the disturbance from a wave
What affects the speed of longitudinal and transverse waves?
state of matter
temperature of matter
type of medium
How does the frequency of a wave affect the period of a wave?
they are inversely proportional
How will the frequency of a wave affect the wavelength of a wave
they are inversely proportional
as frequency decreases wavelength increases
How does the velocity of a wave affect the frequency of a wave
they are directly proportional
Three main notes about waves
waves carry energy
waves carry the energy but not the matter with it
all waves are caused by something vibrating
The material through which a wave travels is called a ___
medium
why do waves not go on forever?
energy will change forms
If the amplitude of a wave changes, which also changes?
the energy the wave carries
The process by which sound waves transfer their energy is called _____
conduction
