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WorksheetsPHY7
Total questions: 56
Worksheet time: 1hrs 2mins
what does ultrasound require for motion imaging?
The speeds of the sound and of the moving object
The speed of the sound, and the frequencies of the sound waves emitted and observed
The speeds of the sound and of the moving object, and the frequencies of the sound waves emitted and observed
The speeds of the sound and of the moving object, and the frequencies and wavelengths of the sound waves emitted and observed
how does ultrasound work?
it uses the travel time of reflected sound waves through the body to calculate distance
distance can be calculated as long as the speed of the traveling object is given
distance can be calculated because the speed of the wave and how long the wave traveled is given
the frequency and wavelengths determine the calculated distance determined
how to determine the harmonic of a standing wave in a closed pipe?
count the number of 1/4 wavelengths
count the number of total wavelengths
count the number of 1/2 wavelengths
count the number of wavelengths x4
how to determine the wavelength of a of pipe closed at both ends
4L/n when n = 1,2,3...
2L/n when n = 1,2,3...
4L/n when n = 1,3,5...
2L/n when n = 1,3,5...
how to determine the wavelength of a of pipe open at both ends
4L/n when n = 1,2,3...
2L/n when n = 1,2,3...
4L/n when n = 1,3,5...
2L/n when n = 1,3,5...
how to determine the wavelength of a of pipe open at one end
4L/n when n = 1,2,3...
2L/n when n = 1,2,3...
4L/n when n = 1,3,5...
2L/n when n = 1,3,5...
in closed pipes what harmonics are standing waves limited to?
odd harmonics because the standing wave in a closed pipe has to have a node at one end and an antinode at the other end.
odd harmonics because the standing wave in a closed pipe has to have a node at both ends.
even harmonics because the standing wave in a closed pipe has to have a node at one end and an antinode at the other end.
even harmonics because the standing wave in a closed pipe has to have an antinode at both ends.
how to determine the harmonic of an open pipe
number of nodes
number of half wavelengths
L = wavelength/2
L = wavelength/4
what is the difference between an open pipe and a closed pipe?
a closed pipe is only closed at one end and supports an antinode and node. an open pipe supports antinodes at both ends
a closed pipe is closed at both ends and supports two nodes. an open pipe supports antinodes at both ends
an open pipe is only open at one end and supports an antinode and node. a closed pipe supports a node at both ends
an open pipe is open at both ends and supports nodes at both ends. a closed pipe is only closed at one end and supports antinodes at both ends
how to visually determine the harmonic of a string attached at both ends
the number of nodes and full wavelengths
the number of antinodes and full wavelengths
the number of half wavelengths
the number of antinodes
what is the second overtone?
3rd harmonic (n=3) for open systems
5th harmonic (n=5) for closed systems
2nd harmonic (n=2) for open systems
3rd harmonic (n=3) for closed systems
what is the first overtone?
3rd harmonic (n=3) for open systems
5th harmonic (n=5) for closed systems
2nd harmonic (n=2) for open systems
3rd harmonic (n=3) for closed systems
has half the wavelength and twice the frequency of the first harmonic
what is the fundamental frequency of a string?
the frequency of the 1st harmonic standing wave (n=1)
the frequency of the 2nd harmonic standing wave (n=2)
the frequency of the 3rd harmonic standing wave (n=3)
the frequency of the 5th harmonic standing wave (n=5)
formula for the wavelength and frequency of a standing wave on a fixed string
wavelength = 2L/n
frequency = nv/2L
wavelength = 4L/n
frequency = nv/4L
open boundaries always correspond to
(a)
what is an open boundary?
boundary that allows maximum oscillation because it isn't really a boundary
boundary that does not allow oscillation
boundary that leads to an antinode
boundary that leads to a node
what is a closed boundary?
boundary that allows maximum oscillation because it really isn't a boundary
boundary that does not allow oscillation
boundary that leads to an antinode
boundary that leads to a node
formula for sound level
dB = log (i/i0)
dB = log (i0/i)
dB = 10 log (i/i0)
dB = 10 log (i0/i)
how is intensity of sound related to distance from the sound?
intensity increases proportional to the square of the amplitude
intensity is inversely proportional to the square of the distance
being 2x as far from a sound makes it 1/4x as intense
being a 1/4x as far from a sound makes it 2x as intense
how is the amplitude of a sound wave related to its intensity?
intensity increases proportional to the square of the amplitude
intensity is inversely proportional to the square of the distance
if amplitude doubles the intensity quadruples
if amplitude quadruples the intensity doubles
as intensity increase, volume
(a)
what is the doppler effect?
relative velocity/speed of sound
when 2 objects are moving in relation to one another the frequencies of the sound they make are altered
objects moving towards each other increases frequency and objects moving away from each other decreases frequency
objects moving towards each other decreases frequency and objects moving away from each other increases frequency
as frequency increases pitch decreases
true
false
what is pitch?
perception of the frequency of a sound
perception of the wavelength of a sound
perception of the velocity of a sound
what is bulk modulus and what is it lowest/highest in?
a measure of an objects resistance to compression
a measure of an objects resistance to expansion
lowest in gases (easily compressed) and highest in liquids and solids (almost impossible to compress)
lowest in liquids and solids (easily compressed) and highest in gases (almost impossible to compress)
what is sound?
a longitudinal wave that transmits through the oscillation of particles in a deformable medium
a transverse wave that transmits through oscillation of particles in a deformable medium
parallel displacement and velocity
perpendicular displacement to velocity
what is an overtone?
an object that produces multiple frequency waves when struck
higher frequency waves made by object that has multiple frequency waves when struck
lower frequency waves made by object that has multiple frequency waves when struck
an object that produces one frequency wave when struck
what is resonant frequency?
the one basal level natural frequency at which an object vibrates
the natural frequency or frequencies at which an object vibrates
the one basal level wavelength at which an object vibrates
the natural wavelength(s) at which an object vibrates
what is an antinode?
any point on a standing wave where interference is maximized and the amplitude is greatest
a point on a standing wave at which there is no amplitude
any point on a standing wave where interference is minimized and the amplitude is smallest
any point on a standing wave where interference is maximized and the amplitude is smallest
what is an node?
any point on a standing wave where interference is maximized and the amplitude is greatest
a point on a standing wave at which there is no amplitude
any point on a standing wave where interference is minimized and the amplitude is smallest
any point on a standing wave where interference is maximized and the amplitude is smallest
what is a standing wave?
a wave that appears to be stationary because of the interference pattern of the two waves that make it
a wave that appears to be stationary because of the frequency pattern of the two waves that make it
can only be observed in closed end wave systems
can only be observed in open end wave systems
how do waves behave when fixed at one end?
the wave hits the boundary on the fixed end and reflects its direction and inverts
the wave hits the open end and reflects its direction and inverts
the wave hits the boundary on the fixed end and keeps its original direction
the wave hits the open end and only inverts itself
what is constructive interference?
when waves are in phase
when waves are out of phase
the sound heard is increased
the sound heard is decreased
what is deconstructive interference?
when waves are 180 degrees out of phase
when waves are completely out of phase
when waves are in phase
sound heard increases
sound heard decreases
how are two waves in phase described?
waves have a phase difference of 0 degrees and are lined up
waves have a phase difference of 0 degrees and are not lined up
constructive interference
deconstructive interference
what is the phase difference between waves?
the extent to which the waves are offset
extent to which the waves are in line with each other
the higher the phase difference the more offset the wave
the lower the phase difference the more offset the wave
what is the principle of superposition?
the displacement of the resultant wave of two interacting waves will be equal to the sum of the displacements of the two interacting waves
the displacement of the resultant wave of two interacting waves will be equal to the difference of the displacements of the two interacting waves
waves add when they have the same sign and subtract when they have opposite signs
waves add when they have different signs and subtract when they have opposite signs
what is amplitude in the context of waves?
the maximum possible displacement for a wave
the minimum possible displacement for a wave
how far away from the equilibrium position the point on the wave is
how close the equilibrium position is to the point on the wave
what is displacement in the context of waves?
the maximum possible displacement for a wave
the minimum possible displacement for a wave
how far away from the equilibrium position the point on the wave is
how close the equilibrium position is to the point on the wave
what is angular frequency?
measurement of how many radians (2pi) a wave rotates per second
measurement of how many radians (pi) a wave rotates per second
measurement of how many radians (2pi) a wave rotates per minute
measurement of how many radians (pi) a wave rotates per minute
what is a period?
the number of seconds it takes a wave to complete one oscillation
the number of seconds it takes a wave to complete one wavelength
the number of seconds it takes a wave to complete one frequency
the number of seconds it takes a wave to complete one vibration
what is frequency?
the number of seconds it takes a wave to complete one oscillation
the number of full oscillations a wave completes in one second
the number of full oscillations a wave completes in one amplitude
the number of seconds it takes a wave to complete a half oscillation
which of the following is true of light and sound waves?
light waves are transverse waves and sound waves are longitudinal waves
light waves are longitudinal waves and sound waves are transverse waves
light waves and sound waves are both longitudinal
light waves and sound waves are both transverse
what is a longitudinal wave?
oscillates in the same directions as the movement of the wave
a wave that is parallel to the direction of energy transfer
oscillates perpendicular to the movement of the wave
a wave that is perpendicular to the direction of energy transfer
what is a transverse wave?
oscillates in the same directions as the movement of the wave
a wave that is parallel to the direction of energy transfer
oscillates perpendicular to the movement of the wave
a wave that is perpendicular to the direction of energy transfer
formula for velocity of a wave
v = frequency x wavelength
v = frequency x amplitude
v = wavelength x period
v = wavelength x Planck's constant
In the mid-1800s, scientists observed four visible lines in the emission spectrum of the hydrogen atom. These lines had wavelengths of 410 nm, 434 nm, 486 nm, and 656 nm, where 1 nm = 10–9 m. This series of lines is part of what became known as the Balmer series, after Johann Balmer demonstrated that their wavelengths λ could be described by the equation
Although this equation worked, it was some time before scientists understood why it worked.
In the early 1900s, Niels Bohr proposed that the electron in a hydrogen atom could exist only in certain quantized energy states. These states were given by the equation E = –13.6/n2 eV. He further proposed that when an electron moved from a higher energy state to a lower one, the excess energy was released as a packet, or quantum, of light known as a photon. The corresponding wavelength of a photon could then be found with the equation λ = hc/E, where E is the energy of the photon, h = 4.1 × 10–15 eV•s is Planck’s constant, and c = 3 × 108 m/s is the speed of light. The Bohr model was in excellent agreement with the Balmer series and gave clues to the quantum nature of atoms.
If the wavelength of a light beam were doubled, its frequency would be:
halved
quartered
doubled
quadrupled
If the energy of a photon is doubled, which of the following properties of the photon will also double?
Amplitude
Wavelength
Frequency
Intensity
If the red line in the Balmer series has a wavelength of 656 nm, which of the following is closest to its frequency?
4.6 × 1014 Hz
4.6 × 10−14 Hz
2.1 × 1015 Hz
2.1 × 10−15 Hz
Which of the following is closest to the wavelength of a photon whose energy is 2 eV?
740 nm
620 nm
450 nm
310 nm
Smoke detectors fall into two major classes. Ionization detectors, the most common units, contain two parallel electrodes that are typically separated by 3 cm with a 5-V potential difference across them. The air molecules between the electrodes are ionized by collisions with helium nuclei that are produced by a radioactive source. Most units are initially fueled with 60 million nuclei of radioactive americium 241 (half-life 430 years). The now-ionized air molecules drift toward one of the electrodes with an average speed of 0.1 m/s and thus support a small current between the two electrodes. Smoke particles that enter and combine with the ions reduce the current and initiate an alarm.
Photoelectric detectors, by contrast, contain a light-emitting diode that sends a beam of unpolarized light across a small chamber. The light beam usually has a wavelength of 6.0 × 10–7 m and has an intensity of 1.0 × 10–3 W. When smoke particles enter the chamber, the light scatters in all directions. A photocell then senses either the increase in the scattered light or the reduced intensity of the light beam and sets off the alarm. The speed of light in air is 3.0 × 108 m/s.
Ionization detectors respond faster to the large smoke particles of flaming fires; photoelectric detectors sense the small particles of smoldering fires more quickly. Modern units have both types of detectors.
When fewer than 3.75 × 106 americium nuclei remain, the ionization smoke detector will not operate due to insufficient ionization. How much time will pass before there are this many nuclei remaining?
1720 years
2150 years
4300 years
6880 years
The explanation for the fact that radioactive isotopes of an element exhibit the same chemical behavior as the stable isotopes of the element is that each has the same:
atomic number
number of neutrons
mass number
atomic weight
What is the magnitude of the electric field between the two electrodes in ionization type detectors?
1.5 N/C
1.66 N/C
15 N/C
166 N/C
The frequency of the light used in photodiode detectors is:
1.8 × 1012 Hz.
5 × 1012 Hz.
1.8 × 1014 Hz.
5 × 1014 Hz.
Destructive interference occurs in photodiode detectors when direct and scattered light rays take paths to the photocell that differ in phase by:
0 degrees
90 degrees
180 degrees
360 degrees
Advanced photodiode detectors have a second light-emitting diode, operating at a wavelength of 2.0 × 10–7 m, to detect even smaller smoke particles from smoldering flames. What is the frequency difference between the two light beams?
12.0 × 1015 Hz
3.0 × 1015 Hz
2.0 × 1015 Hz
1.0 × 1015 Hz
The timbre, or quality, of a musical tone depends on the number and relative strengths of the harmonics including the fundamental frequency of the note. Figure 1a illustrates the first three harmonics of a tone. The addition of the first two harmonics is pictured in Figure 1b, and the addition of the first 3 harmonics is shown in Figure 1c.
Figure 1Elements of a complex tone
The graphs in Figure 2 illustrate the characteristics of two adjacent tones from a bassoon. Figure 2a shows the pressure variations and the amplitudes of the harmonics for one of the tones, and Figure 2b shows the same information for the other tone.
Figure 2Pressure variations and amplitudes of harmonics for adjacent bassoon tones
Which of the waveforms shown in Figure 1 has the shortest period?
first harmonic
second harmonic
third harmonic
the waveform in Figure 1c
At the second position where the three curves intersect in Figure 1a, the curves are all:
in phase
out of phase
at zero displacement
at maximum displacement
If the frequency of the first harmonic in Figure 2a is 100 Hz, what is the period of the second harmonic?
0.005 sec
0.01 sec
0.05 sec
0.02 sec
Which of the following graphs best illustrates the relative amplitudes of the harmonics in Figure 1?
If a fourth harmonic exists for the tone graphed in Figure 1, then, compared to the third harmonic, the fourth harmonic will have:
lower amplitude
higher amplitude
lower frequency
higher frequency
The period of the waveform shown in Figure 1c is the:
same as the period of the first harmonic.
same as the period of the second harmonic.
same as the period of the third harmonic.
sum of the periods of the first, second, and third harmonics.
The wavelength of a radio wave measured by a stationary receiver differs from the emitted wavelength when the transmitter is moving. The frequency measured by the receiver also changes when the transmitter is moving. Three experiments were conducted to determine relationships between the speed of a moving radio transmitter and the changes in wavelength and frequency measured at the receiver. In each of the experiments, a jet flew at constant altitude and emitted a signal that was measured by a receiver on the ground.
Experiment 1
The jet flew directly away from the receiver at 268 m/s. Signals with different frequencies (f) and wavelengths (λ) were transmitted in four trials. The transmitted frequencies and wavelengths are listed in Table 1 along with the measured changes in frequency and wavelength.
Table 1Changing Transmitted f and λ with Constant Jet Speed Away from Receiver
Experiment 2
The frequency of the transmitted radio signal was kept constant at 2.0 x 106 Hz, and the transmitted wavelength was kept constant at 150 m as the jet flew directly away from the receiver at the four different speeds listed in Table 2.
Table 2Constant Transmitted f and λ with Different Jet Speeds Away from Receiver
Experiment 3
The frequency of the radio signal was kept constant at 2.0 x 106 Hz and the wavelength was kept constant at 150 m as the jet flew directly toward the receiver with the two speeds listed in Table 3.
Table 3Constant Transmitted f and λ with Different Jet Speeds toward Receiver
A stationary receiver detects a change in frequency of the signal from a jet flying directly away from it at 300 m/s. Which of the following receivers will detect the same change in frequency from a jet moving away at 600 m/s?
A receiver moving at 900 m/s in the opposite direction as the jet
A receiver moving at 300 m/s in the opposite direction as the jet
A stationary receiver
A receiver moving at 300 m/s in the same direction as the jet
Which of the following graphs best illustrates the relationship between speed of the transmitter away from the receiver and the increase in wavelength of the received signal?
As the speed of the jet flying away from the receiver increases, what happens to the distance between adjacent peaks of the transmitted waves, as measured at the receiver?
It decreases.
It remains constant.
It increases.
It changes, but is not dependent on the speed.
Why are the percentages of the change in frequency and wavelength much greater when sound waves are used instead of radio waves in these experiments?
Sound waves travel more slowly.
Sound waves have a much higher frequency.
Sound waves have a much shorter wavelength.
Interference in the atmosphere affects sound waves much more.
A receiver is in a jet flying alongside another jet that is emitting 2.0 x 106 Hz radio waves. If the jets fly at 268 m/s, what is the change in frequency detected at the receiver?
0 Hz
0.90 Hz
1.79 Hz
3.58 Hz
An astronomer observes a hydrogen line in the spectrum of a star. The wavelength of hydrogen in the laboratory is 6.563 x 10-7m, but the wavelength in the star’s light is measured at 6.56186 x 10-7m. Which of the following explains this discrepancy?
The star is moving away from Earth.
The wavelength of light that the star is emitting changes constantly.
The frequency of light that the star is emitting changes constantly.
The star is approaching Earth.
When a sound source moves away from an observer, the observer has the impression that the sound source is:
rotating.
louder than it actually is.
lower in frequency than it actually is.
higher in frequency than it actually is.
Consecutive resonances occur at wavelengths of 8 m and 4.8 m in an organ pipe closed at one end. What is the length of the organ pipe? (Note: Resonances occur at L = nλ/ 4, where L is the pipe length, λ is the wavelength, and n = 1, 3, 5,…)
3.2 m
4.8 m
6.0 m
8.0 m
The intensity level in decibels is defined as 10 log10(I/I0), where I0 is a reference intensity equal to the human threshold of hearing, 10–12 W/m2. What is the intensity of the threshold of pain, 120 decibels?
1012 W/m2
10° W/m2
10–2 W/m2
10–12 W/m2
A student performs an experiment to determine the distance moved and velocity of a projectile as a function of time.
A 1.00-kg object is initially at rest. The student applies a force of 19.6 N through a distance of 0.50 m to propel the object straight upward. It has an initial speed v and reaches a peak height h above the launch point.
The projectile contains a small speaker that emits a sound at a frequency of 170 Hz. The sound is detected by a microphone and recording device located on the ground directly beneath the vertical trajectory of the projectile. The recorded data are used to compute the velocity of the object using the Doppler effect. (The acceleration due to gravity at the surface of Earth is 9.80 m/s2. Air resistance may be neglected. The speed of sound in air is 340 m/s.)
How much work is done in launching the object?
9.80 kg m/s2
19.6 J
9.8 J
19.6 N
The mathematical expression for h is:
mv2/2.
v2/(2g).
mg
mv
The wavelength of the detected sound when the projectile is at h is:
0.50 m
1.70 m
2.00 m
170 m
What is the magnitude of the detected sound frequency shift from 170 Hz during the projectile flight described in the passage?
It falls to zero, then increases.
It is constant throughout the flight.
It rises continuously.
It falls continuously
The intensity level of Sound B is 20 dB greater than the intensity level of Sound A. How many times greater is the intensity level of Sound B than the intensity level of Sound A?
2
10
20
100
In order to determine the relative speed of approach of a sound source by Doppler measurements, three of the following items of data are necessary. Which one is NOT required?
The speed of sound in the medium
The frequency of the emitted sound
The frequency of the observed sound
The distance between source and observer
