Chapter 7 Waves and Sound Flashcards
Transverse waves definition and examples
-waves in which the direction of particle oscillation is perpendicular to the movement (propagation) of the wave
“the wave” in crowds, electromagnetic waves like visible light, microwaves and x-rays
-particles are oscillating perpendicular to the direction of energy transfer
Longitudinal waves
- waves in which the particles of the wave oscillate parallel to the direction of movement (propagation) meaning the wave particles are oscillating in the direction of energy transfer
- ex- sound waves, laying a slinky flat on a table top and tapping it on the end
Wavelength definition
the distance from one maximum (crest) of the wave to the next
Frequency
The number of wavelengths passing a fixed point per second
-measured in hertz (Hz) or cycles per second (cps)
Speed (v) equation
v= frequency x wavelength
Period (T) definition and equation
- inverse of frequency, the number of seconds per cycle
- T= 1/frequency
Displacement (x) in a wave describes
how far a particular point on the wave is from the equilibrium position
Amplitude (A)
the maximum magnitude of displacement in a wave- NOT total displacement, which would be double the amplitude
Timbre
The quality of sound
-determined by the natural frequency or frequencies of the object
Forced Oscillation
if a periodically varying force is applied to a system, the system will then be driven at a frequency equal to the frequency of the force
Damping
A decrease in amplitude of a wave caused by an applied or nonconservative force
Frequency of sound
Pitch- lower frequency=lower pitch
Infrasonic waves
sound waves with frequencies below 20 Hz
Ultrasonic waves
sound waves with frequencies above 20,000 Hz
Doppler Effect
Describes the difference between the actual frequency of a sound and its perceived frequency when the source of the sound and the sounds detector are moving relative to one another
-moving toward each other- perceived frequency(f1) is greater than the actual frequency (f)
Shock wave
when an object that is producing sound while traveling at or above the speed of sound allows wave fronts to build upon one another at the front of the object (creating a larger amplitude at that point). The highly condensed wave front is a shock wave
-can cause physical disturbances as it passes through other objects
Sonic boom
-the passing of a shock wave that creates a very high pressure followed by a very low pressure
Intensity
the average rate of energy transfer per area across a surface that is perpendicular to the wave
- (power transported per unit area)
- units of W/m^2 (watts per square meter
Intensity equation
I=P/A where P is the power and A is the area
Amplitude and intensity relationship
intensity is proportional to the square of amplitude
-doubling the amplitude produces a sound wave that has four times the intensity
Intensity and distance relationship
-intensity is inversely proportional to the square of the distance from the source
Attenuation
- Damping
- The presence of a nonconservative force causes the system to decrease in amplitude during each oscillation
- does not have an effect on the frequency of the wave, so the pitch will not change
- explains why it is more difficult to hear in a confined or cluttered space: friction from the surfaces of the objects in the room decreases the sound waves amplitude
Standing waves form whenever
whenever two waves of the same frequency traveling in opposite directions interfere with one another as they travel through the same medium
Ultrasound
-uses high frequency sound waves outside the range of human hearing got compare the relative densities of tissues in the body
Doppler ultrasound
-Used to determine the flow of blood within the body by detecting the frequency shift that is associated with movement toward or away from the receiver
