Physics Exam #3 Flashcards
Define Waves
is a moving disturbance that transfers energy through matter or space.
Ex: water, sound, light, micro, x-ray, ultraviolet, seismic, human (waves)
Crest
the highest point of a transverse wave
Trough
the lowest point of a transverse wave
Wavelength
the distance between one point on a wave and the exact same point on the next wave.
Amplitude
the maximum extent of vibration or the distance from the resting position of the medium to the crest or trough
Frequency
the number of waves produced in a given amount of time
Mechanical Waves
waves the require a medium to transfer energy
Ex: ocean, sound waves, water waves, seismic waves
Electromagnetic Waves
waves that go through vacuums, can transfer energy through a medium or empty space.
Ex: radio, light, infared, ultraviolet, x-rays, gamma rays (waves)
Medium
something through which a wave travels
solids, liquids, gas
Ex: water wave the medium is water; sound wave = sound; earthquake = ground
Transverse Waves
the particles of a medium vibrate in opposite (perpendicular) direction of the direction the wave is traveling.
Ex: take the form of light
Longitudinal Waves
Particles move parallel to the direction of the wave and come in the form of sound
compressions
the squished-up part of the longitudinal wave
Rarefactions
the spread-out part of the longitudinal wave
Light Wave Example
transverse wave
Micro Wave Example
Microwaves
Sound Wave Example
Choir singing
Water Wave Example
Wave of water (dropping a rock in the water)
Radio Wave Example
Bluetooth
X-Ray Wave Example
x-ray, mammorgraphyU
UV Ray Example
Tanning Beds
Seismic Wave Example
Earthquakes
EM Spectrum
The electromagnetic spectrum is the range of all types of electromagnetic radiation.
How does sound Work?
Sound waves move through matter by making the particles of the medium vibrate.
For example, when you hit a drum, the drum vibrates, and the sound waves travel through the air to your ears.
Objects that vibrate slowly produce low-pitched sounds, while objects that vibrate quickly produce higher-pitched sounds.
It can travel through solids, liquids, gases
Properties: volume, pitch, amplitude, frequency.
How Does sound change in different Media?
Solids:
Travels fastest through solids because the particles in solids are closer together, allowing sound waves to travel more efficiently.
Travel further without losing much energy
Example: Drums
Liquids:
Travels slower through liquids than solids but faster than through gases. Particles are less tightly packed than in solids, so sound waves encounter more resistance.
Sonar: a way to use sounds to locate in water (bats/dolphins)
Gases:
Travels slowest through gases because the particles in gases are far apart. Sound waves have to push against air molecules; causing energy to be lost quickly.
Sound from a bell, horn, alarm clock
Overview of Sound
Sound travels fastest through solids, slower through liquids, and slowest through gases due to the difference in particle arrangement and density in each medium.
Pitch
how high or low a sound is
Volume
how loud or soft a sound is
Ultrasound
sound waves with frequencies above the normal human range of hearing (20-100 kHz)
Infrasound
Sounds with frequencies below the normal range of hearing (20-200 kHz)
Outer Ear:
Catches the sound wave
Middle Ear
takes the sound waves and vibrates the eardrum
Inner Ear
Sends the messages to the brain
Brain
puts it together so you can understand the sounds
Doppler Effect
Is the apparent change in the frequency of a sound caused by the motion of either the listener or the source of the sound
Long Wavelength/Low Frequency
Small Wavelength/High Frequency
The Doppler Effect for moving sound source
Resonance
the frequency of sound waves exactly matches the natural frequency of an object
Period
amount of time it takes for one cycle to pass a given point
T = 1/f
Opaque
does not allow light to pass through. ALl light absorbed or reflected
Ex: wood, table
Translucent
can be seen through but not clearly. Allows some light to go through, but some is absorbed or reflected.
Ex: wax paper, tissue paper, shades
Transparent
almost allows all light to go through, so it can be seen through clearly (trans= across)
Ex: window glass, diamond, glass lens, contacts
How do we see objects?
Light reflects off them and back to our eyes
How do we see colors?
the objects reflect that color of white light, and it absorbs all of the other colors.
Subtractive System of Color
Objects create color by subtracting and absorbing certain wavelengths of color while reflecting other wavelengths back to the viewer
Uses colorants and reflected light
Cyan, magenta, and yellow
Additive System of Color
Light is emitted directly from a source before an object reflects light.
Red, blue and green
Primary and Secondary Colors of LIGHT
Primary: Red, Blue, Green
Secondary: Yellow, Cyan, Magenta
Primary and Secondary Colors of PIGMENT
Primary: Yellow, Cyan, Magenta
Secondary: Red, Blue, Green
Reflection (Regular/Diffuse)
When light bounces off an object.
Regular:
When an object’s surface is smooth, and you see an image.
Example: a plant (flat) mirror
Diffuse:
where a rough surface scatters light in many directions and no image appears.
Ex: paper is rough enough to scatter light so there is no image.
Refraction
light slows down as it goes from space to air. It slows down even more in water and glass.
Why? Atoms get in the way
Ex: use a lens to curve light on purpose
Convex Lenses
(or position) lenses converge (or focus) light and can form images.
Ex: magnifying glass, telescope, microscope, binoculars, eyeglass, far-sightedness, camera, projectors
Concave Lenses
(or negative) lenses diverge (or spread out) light rays
Polarizing Lenses
have special chemical applied to them to filter light the chemical molecules ar elined up specifically to block some of the light from passing through lens. Slits only allow one light to go through.
Concave Mirrors
image shows in from the mirror, image different in size
Convex Mirror
The reflective surface bulges toward the light source
Near Sightedness
light focuses in front of the retina
Far-sightedness
light focuses behind the retina
Law of Reflection
Angle of Incidence = Angle of Reflection
On a flat mirror
Incidence = the created light by objects
The angle of Reflection = image of the object
Diffraction
is the slight bending of light as it passes around the edge of an object.
The amount of bending depends on the relative size of the wavelength of light to the size of the opening.
If the opening is much larger than the light’s wavelength, the bending will be almost unnoticeable.
