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Chapter 15 & 16 Physics

Terms in this set (45)

Sound
a pressure oscillation that is transmitted through matter
-only produced when there are oscillation in pressure
Sound waves
-move through air bc of regular vibrations in air pressure
-a pressure variation transmitted through matter as a longitudinal wave
-long waves (parallel) because vibration of air is parallel to the direction of motion
tuning fork in water
-vibration of tuning fork is transmitted to water -> water vibration-> wave
Slinky model
-long wave can show that loops are high, highly compressed w low/high density loops
Ballon
-See how wave moves in 3D
-spreads out in all directions like sound
-energy density decreases with distance (not due to friction like for slinky)
speed depends on air temp
as t increases, velocity of air molecules increases so the molecules respond quicker
speed depends on density of medium
as density increases, distance between molecules decreases, so they respond sooner to being bumped
Fastest sound medium
Gas is slowest, liquid is second fastest, sound goes fastest in solid
-do not travel in vacuum bc no medium
sound detectors
transform kinetic energy of pressure wave particles into another form of energy
-ears make waves into electrical impulses
What makes sound waves different if they are just pressure waves
amplitude (loudness) and frequency (pitch)
Pitch (Hz)
-the highness of sound depends on frequency or wavelengths of a pressure wave
-Humans can hear from 20 thru 20,000 Hz
-high note on piano 4186 hz
-cats, dogs, bats, horses, and dolp can hear higher than us
-horses and elephants can hear lower than us
-corresponds to frequency
equation
Loudness (pa)
-human hearing is a factor of a million
- intensity of a sound wave as perceived by the ear and interpreted by the brain; depends on amplitude and pressure wave
-humans can hear from 2 x 10^-5 to 20 PA
-1 atm of pressure = 1.01 x 10^-5 PA
-brains interpretation of intensity
How does the pitch of a tuning fork change as the magnitude of its vibration changes ?
trick question.. it does not
amplitude (or intensity) of a sound wave
-a measure of the variation in pressure of a medium
-decibel used in larger ranges
Decibels
-used in larger ranges (dB)
-for every x of 10 = +20 dB
-unit for sound level
Doppler Effect
change in frequency of sound caused by the movement of either the source or the detector, or both
-fd = frequency at detector
-fs = frequency emitted by source
-v = speed of sound in the medium
-vd = velocity of detector
-vs = velocity of source
-used by astronomers, police officers, and dr's for heartbeats
equation
the color blue
represents that it is fast
-therefore material is dense and cold
-pink or lighter is slow (hot)
Sound level
the logarithmic scale that measures the amplitudes of sounds that humans can hear
beat
the oscillation of wave amplitude heard when two frequencies are nearly identical
consonance
a pleasant combo of pitches
open pipe resonator
a resonating tube with both ends open
-here a pressure of a reflected wave is inverted
-only has resonance if there are nodes at both ends
closed pipe resonator
a resonating tube with one end closed from air
-a column length of wavelength/4 is in a resonance with a tuning fork
harmonics
multiples of the fundamental frequency
dissonance
an unpleasant combo of pitches
Standing wave
-when this is created, resonance occurs
-in a standing sound wave in a pipe , nodes are regions of mean atm pressure and low displacement
-two antinodes are separated by one half wavelength
illuminance
the illuminance of a surface
diffraction
the bending of light as it passes the edge of a barrier
luminous flux
a measure of the total rate at which light is emitted from a source
polarized
Light that oscillates with a specific pattern
secondary color
a color formed 2 primary colors of light
luminous source
an object that emits light
-lightbulbs
ray model of light
uses straight lines to describe how light interacts with matter
-light travels in straight line
transparent
a material that transmits light clearly
red
a primary color that forms white light when mixed with green and blue blight
primary pigment
absorbs only one primary color from white light
secondary pigment
absorbs two primary colors of light (cyan, magenta, and yellow)
translucent
a material that transmits light, but objects cannot be seen clearly through it
opaque
a material that transmits no incident light
Malus's law
shows that reduction of light intensity as it passes through a second polarizing filter
how long does light from the sun take to reach earth's orbit?
8 min
Which choice best describes an inverse-square relationship?
daylight on mars is dimmer than daylight on earth
area of the surface of a sphere
c
What does a primary pigment absorb from white light?
one primary color
what does a secondary pigment absorb from the white light
two primary colors
pigments
-primary pigments: cyan, yellow, magenta
-secondary pigments: red, green, blue
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