Waves
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● A mechanical wave is created when
a source of energy causes a
vibration to travel through a
medium.
● mechanical wave: Is a disturbance in matter
that carries energy from one place to another.
● The three main types of mechanical waves are
transverse waves, longitudinal waves,and surface
waves.
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transverse wave:Is a wave that cause the medium to vibrate at right angles to the
direction in which the waves travel.
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longitudinal wave:Is a wave in which the vibration of the medium is parallel to the
direction the wave travels.
Surface wave:Is a wave that travels along a surface separating two media.
Transverse,longitudinal,Surface Waves
● A wave’s frequency equals the frequency
of the vibrating source producing the
wave.
○ Frequency: which is the number of complete cycles
in a given time.
Frequency
● Increasing the frequency of a wave
decrease its wavelength.
○ Wavelength:Is the distance between a point
on one wave and the same point on the next
cycle of the wave.
Wavelength
● For waves traveling at a given speed,
wavelength is inversely proportional to
frequency .
● The more energy a wave has, the greater
is its amplitude.
○ Amplitude:Is the maximum displacement of
the medium from its rest position
● A reflected wave has a smaller amplitude
than the original wave because it loses
some energy during reflection.
○ Reflection:Does not change the speed or
frequency of a wave,but the wave can be
flipped upside down
● When a wave enters a medium at an
angle, refraction occurs because one side
of the wave moves more slowly than
other side.
○ Refraction:The bending of the wave as it
enters a new medium at an angle
● The larger the wavelength is compared
to the size of an opening or obstacle, the
more a wave diffracts.
● The types of interferences are
constructive interference and
destructive interference.
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Interference:Occurs when two or more waves overlap and combine together.
Constructive Interference:Occurs when two or more waves combine to produce
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a wave with a larger displacement.
Destructive Interference:Occurs when two or more waves combine to produce a
wave with a smaller displacements.
● A standing wave forms only if half a
wavelength or a multiple of half a
wavelength fits exactly into the length of
the vibrating object.
● Many behaviors of sound can be
explained using a few properties-speed,
intensity and loudness,and frequency and
pitch.
○ Intensity:Is the rate at which a waves
energy flows through a given area
○ Pitch:Is the frequency of a sound as you
perceive it
● Ultrasound is used in many applications,
including sonar and ultrasound imaging.
● As a source of sound approaches,an
observer hears a higher frequency.When
the sound source moves away,the
observer hears a lower frequency.
The outer ear gathers and focuses sound
into the middle ear,which receives and
amplifies the vibratons.The inner ear uses
nerve endings to sense vibrations and send
singals to the brain.
● Sound is recorded be converting sound
waves into electrical signals that can be
processed and stored.Sound is
reproduced be converting electrial
signals back into sound waves.
● Most instruments vary pitch by changing
the frequency of standing waves.
● Electromagnetic waves are produced
when an electric charge vibrates or
accelerates.
○ Electromagnetic waves:Transverse waves
consisting of changing electric fields and
changing magnetic fields.
● Electromagnetic waves can travel
through a vacuum,or empty space,as
well as through matter.
● The speed of light in a vaccum,c, is 3.00
X 10^8 meters per seconds.
● Electromagnetic waves vary in
wavelength and frequency
● Electromagnetic radiation behaves
sometimes like a wave and sometimes
like a stream of particles.
○ Electromagnetic radiation:The transfer of
energy by electromagnetic waves traveling
through matter or across space.
● The intensity of light decreases as
photons travel farther from the source.
● The electromagnetic spectrum include
radio waves infrared rays,visible light,
ultraviolet rays, X-rays,and gamma rays.
○ Electromagnetic spectrum:the full range
frequencies of electromagnetic radiation.
● Radio waves are used in radio and
television technologies,as well as in
microwave ovens and radar.
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Scattering:Means that light is redirected as it passes through a medium.
Opaque:Materials either absorbs or reflects all of the light that strikes.
Image:Is a copy of an object formed by reflected or refracted waves of light.
Mirage:Is a false or distorted image.
Scattering:That light is redirected as it passes through a medium.
Polarized light:Light with waves that vibrate in only one plane.
Diffuse reflection:Occurs when parallel light waves strike a surface and reflect all in the same
direction.
Regular reflection:Occurs when parallel light waves strike a rough uneven surface and reflects
in many different directions.