1.
___________: Particle motion and wave velocity parallel.
Explanation
A longitudinal wave is a type of wave in which the particle motion and wave velocity are parallel. In other words, the particles of the medium through which the wave is traveling move back and forth in the same direction as the wave itself. This is in contrast to transverse waves, where the particle motion is perpendicular to the wave velocity. Therefore, the given answer of "longitudinal wave" or "longitudinal waves" accurately describes the relationship between particle motion and wave velocity in this type of wave.
2.
___________: In air, its value is 344 m/s at 20 degrees Celsius.
Explanation
The given statement is explaining the concept of the speed of sound. It states that in air, the speed of sound is 344 m/s at 20 degrees Celsius. This means that sound waves travel through air at a rate of 344 meters per second at this specific temperature. The speed of sound can vary depending on the medium it is traveling through, such as air, water, or solids.
3.
___________: Vibrating electric and magnetic fields.
Explanation
The given statement describes "Vibrating electric and magnetic fields," which is a characteristic of electromagnetic waves. Electromagnetic waves are a form of energy that can travel through space and are created by the oscillation of electric and magnetic fields. These waves include various types such as radio waves, microwaves, infrared waves, visible light, ultraviolet waves, X-rays, and gamma rays. Therefore, the correct answer is "electromagnetic waves."
4.
___________: Maximum displacement of wave particle.
Explanation
The term "amplitude" refers to the maximum displacement of a wave particle from its equilibrium position. In other words, it represents the maximum distance that the particle moves away from its resting point during the oscillation of a wave. The greater the amplitude, the more energy the wave carries and the more intense the wave appears. Therefore, amplitude directly correlates with the maximum displacement of a wave particle.
5.
___________: Indicates movement of a receding source.
Explanation
Redshift refers to the phenomenon where light from a source appears to be shifted towards longer wavelengths, indicating that the source is moving away from the observer. This is due to the Doppler effect, which causes the wavelength of light to stretch as the source moves away. Therefore, redshift can be used to identify the movement of a receding source.
6.
___________: Time to travel one wavelength.
Explanation
The period is the time it takes for a wave to complete one full cycle or travel one wavelength. It is a measure of the wave's frequency, indicating how many cycles or wavelengths occur in a given time. The period is typically expressed in units of seconds and is inversely related to the frequency of the wave. As the frequency increases, the period decreases, meaning the wave completes more cycles or wavelengths in a shorter amount of time.
7.
___________: Waveforms caused by wave interference.
Explanation
The given answer, "standing waves" or "standing wave," is the correct answer because it accurately describes the type of waveforms caused by wave interference. Standing waves occur when two waves of the same frequency and amplitude traveling in opposite directions interfere with each other, resulting in a pattern that appears to be standing still. This phenomenon is commonly observed in various systems, such as musical instruments, where certain frequencies create standing waves and produce distinct harmonics.
8.
___________: Longitudinal waves that propagate through matter.
Explanation
Sound is the correct answer because it is a type of longitudinal wave that can travel through matter. Longitudinal waves are characterized by the vibration of particles in the same direction as the wave is moving, and sound waves exhibit this behavior. Sound waves can travel through various mediums such as air, water, and solids, and they are responsible for the sensation of hearing.
9.
___________: Propagation of energy after a disturbance.
Explanation
The given answer, "Waves," is the correct response because waves are a means by which energy is transmitted through a medium or space after a disturbance. Waves can take various forms, such as sound waves, light waves, or water waves, and they carry energy from one location to another without the actual transfer of matter. This makes waves an essential phenomenon in understanding the propagation of energy.
10.
___________: Maximum energy transfer to a system.
Explanation
Resonance refers to the phenomenon where a system oscillates with maximum energy transfer at its natural frequency. This occurs when the frequency of an external force matches the natural frequency of the system, causing it to vibrate with maximum amplitude. Therefore, resonance allows for maximum energy transfer to the system, making it the correct answer.
11.
___________: Rate of transfer of sound energy through a given area.
Explanation
Intensity is the measure of how much sound energy is transferred through a given area. It is directly proportional to the amplitude of the sound wave. Higher intensity means a greater amount of sound energy is being transferred, while lower intensity indicates a lower amount of sound energy. Therefore, intensity is the appropriate term to describe the rate of transfer of sound energy through a given area.
12.
___________: Number of oscillations per time.
Explanation
Frequency refers to the number of oscillations or cycles that occur within a given time period. It is a measure of how often a repetitive event, such as a wave or vibration, occurs in a specific time frame. In other words, frequency quantifies the rate at which something repeats or oscillates. It is typically measured in hertz (Hz), which represents the number of cycles per second. Therefore, the given answer "frequency" accurately describes the concept of the number of oscillations per time.
13.
___________: f > 20,000 Hz
Explanation
Ultrasound refers to sound waves with frequencies higher than 20,000 Hz. This means that the given statement "f > 20,000 Hz" aligns with the definition of ultrasound. Ultrasound is commonly used in medical imaging to create images of internal body structures. It is also used in various other fields such as cleaning, measuring distance, and detecting objects.
14.
___________: 3.00 * 10^8 m/s
Explanation
The given answer "speed of light" is the correct answer because the value "3.00 * 10^8 m/s" represents the speed of light in a vacuum. The speed of light is a fundamental constant in physics, denoted by the symbol "c", and it is the maximum speed at which information or matter can travel in the universe. It plays a crucial role in various scientific theories and has been extensively studied and measured through experiments.
15.
___________: Particle motion perpendicular to wave velocity
Explanation
Transverse wave refers to a type of wave in which the particle motion is perpendicular to the wave velocity. In this type of wave, the particles move up and down or side to side, while the wave itself moves forward. This is in contrast to longitudinal waves, where the particle motion is parallel to the wave velocity. Therefore, the correct answer for the given question is "transverse wave" or "transverse waves".
16.
___________: Equal to lamba/T
Explanation
The given answer, "wave speed," is the quantity represented by the expression "lamba/T." Lambda represents the wavelength of a wave, and T represents the period of the wave. The ratio of wavelength to period gives the speed at which the wave is traveling, which is commonly known as wave speed. Therefore, the expression "lamba/T" is equal to the wave speed.
17.
___________: Regions of sound
Explanation
The term "sound spectrum" refers to the distribution of different frequencies present in a sound. It represents the range of frequencies that can be detected by the human ear, from low frequencies to high frequencies. The sound spectrum is divided into different regions based on these frequencies, allowing us to analyze and understand the characteristics of a sound. Therefore, the answer "sound spectrum" accurately describes the concept of regions of sound based on frequency distribution.
18.
___________: Apparent change of frequency because of relative motion.
Explanation
The Doppler effect refers to the apparent change in frequency of a wave due to the relative motion between the source of the wave and the observer. This effect is commonly observed in everyday life, such as when the pitch of a siren changes as an ambulance passes by. The change in frequency is a result of the compression or stretching of the wavefronts as the source moves towards or away from the observer. This phenomenon is known as the Doppler effect and is responsible for the apparent change in frequency.
19.
___________: Unit equivalent to 1/s
Explanation
A hertz is a unit of frequency, specifically the number of cycles or vibrations per second. It measures the rate at which something occurs or repeats within a given time frame. In this context, it can be understood as a unit equivalent to 1/s, meaning that it represents one cycle or vibration per second.
20.
___________: Distance between two wave maxima.
Explanation
The term "wavelength" refers to the distance between two wave maxima. In other words, it is the length of one complete wave cycle, from one peak to the next. This measurement is commonly used in physics and wave theory to describe the size and characteristics of waves, such as light waves or sound waves. By understanding the wavelength, scientists can analyze and predict various wave behaviors and phenomena.
21.
What is the number of wave cycles for a given period of time called?
Correct Answer
D. Frequency
Explanation
The number of wave cycles for a given period of time is called frequency. Frequency measures how many complete wave cycles occur in a certain amount of time. It is usually measured in hertz (Hz). Wavelength refers to the distance between two corresponding points on a wave, period is the time it takes for one complete wave cycle to occur, and amplitude represents the maximum displacement of a wave from its equilibrium position.
22.
If a piece of ribbon were tied to a stretch string carrying a transverse wave, how would the ribbon be observed to oscillate?
Correct Answer
A. Perpendicular to wave direction
Explanation
The ribbon would be observed to oscillate perpendicular to the wave direction. This is because in a transverse wave, the particles of the medium move perpendicular to the direction of the wave propagation. So, when the wave passes through the ribbon, it would cause the ribbon to move up and down or side to side, perpendicular to the direction in which the wave is traveling.
23.
The energy of a wave is related to the square of which of the following?
Correct Answer
A. Amplitude
Explanation
The energy of a wave is related to the square of its amplitude. The amplitude of a wave represents the maximum displacement of particles in the medium from their equilibrium position. The greater the amplitude, the more energy the wave carries. This is because a larger amplitude means that there is a greater amount of energy being transferred by the wave as it moves through the medium. Therefore, the energy of a wave is directly proportional to the square of its amplitude.
24.
How fast do electromagnetic waves travel in a vacuum?
Correct Answer
A. 3.00 x 10^8 m/s
Explanation
Electromagnetic waves travel at a constant speed of 3.00 x 10^8 m/s in a vacuum. This speed is commonly referred to as the speed of light and is a fundamental constant in physics. It is important to note that this speed remains constant regardless of the wavelength or frequency of the electromagnetic wave.
25.
Which of the following is true for electromagnetic waves?
Correct Answer
D. None of these is true
Explanation
Electromagnetic waves have the same speed in vacuum for all frequencies. They are not longitudinal waves, but rather transverse waves. Unlike mechanical waves, electromagnetic waves do not require a medium for propagation. Therefore, none of the given statements are true for electromagnetic waves.
26.
Which one of the following regions has frequences just slightly less than the visable region in the electromagnetic frequency spectrum?
Correct Answer
D. Infared
Explanation
Infrared radiation has frequencies just slightly less than the visible region in the electromagnetic frequency spectrum. It falls between microwaves and visible light on the spectrum. Infrared radiation is commonly associated with heat and is used in various applications such as remote controls, night vision technology, and thermal imaging.
27.
Sound waves propagate in which of the following?
Correct Answer
D. All the above
Explanation
Sound waves propagate in solids, liquids, and gases because they are mechanical waves that require a medium to travel through. In solids, the particles are closely packed, allowing sound waves to travel quickly and efficiently. In liquids, the particles are less tightly packed, causing sound waves to travel at a slower speed. In gases, the particles are even further apart, resulting in the slowest speed of sound. Therefore, sound waves can propagate in all three states of matter.
28.
What is the lower frequency limit of the audible range of human hearing?
Correct Answer
A. 20 Hz
Explanation
The lower frequency limit of the audible range of human hearing is 20 Hz. This means that humans can perceive sounds with frequencies as low as 20 Hz. Frequencies below this limit are considered infrasound and are typically not audible to humans.
29.
A sound with an intensity level of 30 DB is how many times louder than the threshold of hearing?
Correct Answer
D. 1000
Explanation
The intensity level of a sound is measured in decibels (dB). The threshold of hearing is the lowest level of sound that can be detected by the human ear, which is typically around 0 dB. In this question, the sound with an intensity level of 30 dB is 1000 times louder than the threshold of hearing. This is because the decibel scale is logarithmic, and every increase of 10 dB represents a sound that is 10 times more intense. Therefore, an increase of 30 dB represents a sound that is 10 x 10 x 10 = 1000 times louder than the threshold of hearing.
30.
A moving observer approaches a stationary sound source. What does the observer hear?
Correct Answer
A. An increase in frequency
Explanation
As the observer moves towards the sound source, the distance between them decreases. This causes the sound waves to be compressed, resulting in a higher frequency. Therefore, the observer hears an increase in frequency.
31.
Which of the following properties does NOT change in the Doppler effect?
Correct Answer
B. Speed
Explanation
The Doppler effect is the change in frequency or wavelength of a wave as observed by an observer moving relative to the source of the wave. While the frequency, wavelength, and period of the wave all change in the Doppler effect, the speed of the wave does not. The speed of a wave is determined by the medium through which it is traveling and remains constant regardless of the motion of the source or observer. Therefore, the correct answer is speed.
32.
If an astronomical light source were moving toward us, what would be observed?
Correct Answer
A. A blueshift
Explanation
When an astronomical light source is moving toward us, the observed light waves get compressed, causing a decrease in wavelength and an increase in frequency. This phenomenon is known as the blueshift. As a result, the light appears shifted towards the blue end of the spectrum. This effect is similar to the change in pitch of a sound wave when a moving source approaches an observer, causing a higher frequency, which is why the option "a sonic boom" is not correct in this context.
33.
Which of the following occur(s) when a stretched string is shaken at one of its natural frequencies?
Correct Answer
D. All of these
Explanation
When a stretched string is shaken at one of its natural frequencies, all of the given options occur. This is because when the string is shaken at its natural frequency, it starts to vibrate in a way that creates standing waves. These standing waves are a result of resonance, which is the phenomenon where an object vibrates at its natural frequency when exposed to a matching external frequency. During resonance, the energy transfer between the string and the shaking source is maximized, resulting in maximum energy transfer. Therefore, all of the given options occur when a stretched string is shaken at one of its natural frequencies.
34.
Waves involve the propagation of __________.
Correct Answer
energy
Explanation
Waves involve the propagation of energy. Waves are disturbances that transfer energy from one point to another without transferring matter. This energy can take various forms, such as mechanical waves that require a medium to propagate (like sound waves) or electromagnetic waves that can travel through a vacuum (like light waves). Regardless of the type of wave, energy is always involved in its propagation.
35.
Wave velocity and particle motion are __________ in transverse waves.
Correct Answer
perpendicular
Explanation
In transverse waves, the wave velocity and particle motion are perpendicular to each other. This means that as the wave travels in one direction, the particles of the medium move in a direction that is perpendicular to the wave's direction of travel. This can be visualized by imagining a wave traveling horizontally, while the particles of the medium move up and down vertically. This perpendicular relationship between wave velocity and particle motion is a characteristic of transverse waves.
36.
The distance from one wave crest to an adjacent wave crest is called a __________.
Correct Answer
wavelength
Explanation
The distance from one wave crest to an adjacent wave crest is called a wavelength. This term is commonly used in the study of waves, such as sound waves or electromagnetic waves. It represents the length of one complete wave cycle and is typically measured in meters or other units of length. Understanding the concept of wavelength is important in various fields, including physics, engineering, and telecommunications.
37.
Wave speed is equal to the wavelength times the __________.
Correct Answer
frequency
Explanation
The wave speed is determined by the wavelength and frequency of the wave. The wavelength represents the distance between two consecutive points of the wave, while the frequency refers to the number of complete wave cycles that occur in one second. When these two values are multiplied together, we get the wave speed, which represents the speed at which the wave is traveling through a medium. Therefore, the correct answer is frequency.
38.
In a vacuum, electromagnetic waves travel at the speed of __________.
Correct Answer
light
Explanation
In a vacuum, electromagnetic waves travel at the speed of light. This is because electromagnetic waves are a form of energy that does not require a medium to propagate. Light is an example of an electromagnetic wave, and it travels at a constant speed of approximately 299,792 kilometers per second in a vacuum. This speed is a fundamental constant in physics and plays a crucial role in various scientific theories and calculations.
39.
Radio waves are __________ sound waves.
Correct Answer
not
Explanation
Radio waves are electromagnetic waves, not sound waves. Sound waves require a medium, such as air or water, to travel through, while radio waves can travel through a vacuum. Additionally, sound waves are mechanical waves that require particles to vibrate in order to propagate, while radio waves are a form of electromagnetic radiation that can travel through empty space. Therefore, the correct answer is "not".
40.
Sound waves are __________ waves.
Correct Answer
longitudinal
Explanation
Sound waves are longitudinal waves because they propagate through the compression and rarefaction of particles in a medium. In a longitudinal wave, the motion of the particles is parallel to the direction of wave propagation. This means that the particles move back and forth in the same direction that the wave is traveling. This is in contrast to transverse waves, where the motion of the particles is perpendicular to the direction of wave propagation.
41.
The audible region is above __________ Hz.
Correct Answer
20
Explanation
The audible region refers to the range of frequencies that can be heard by the human ear. In this case, the given answer of 20 Hz indicates that the audible region starts above this frequency. This means that any sound with a frequency below 20 Hz would not be audible to the human ear.
42.
Decibles are used to measure the sound property of __________.
Correct Answer
intensity
Explanation
Decibels are used to measure the sound property of intensity. Intensity refers to the amount of energy that is transmitted through sound waves per unit of time, and it is measured in decibels (dB). Decibels provide a quantitative measure of how loud or soft a sound is, with higher decibel values indicating greater intensity and louder sound. Therefore, intensity is the correct answer to the question.
43.
To double the loudness, or sound intensity, a dB difference of __________ is needed.
Correct Answer
3
Explanation
To double the loudness or sound intensity, a dB difference of 3 is needed. This means that if the initial sound intensity is x dB, then to double it, the sound intensity needs to be increased by 3 dB. The relationship between sound intensity and dB is logarithmic, with every 3 dB increase representing a doubling of the sound intensity. Therefore, a difference of 3 dB is required to achieve a doubling of the loudness.
44.
In the Doppler effect, when a moving sound source approaches a stationary observer, the apparent shift in frequency is __________.
Correct Answer
higher
Explanation
When a moving sound source approaches a stationary observer, the apparent shift in frequency is higher. This is because as the source moves closer to the observer, the sound waves get compressed, resulting in a higher frequency. This compression causes an increase in the perceived pitch of the sound.
45.
A Doppler blueshift in light from a star indicates that the star is __________.
Correct Answer
approaching
Explanation
A Doppler blueshift in light from a star indicates that the star is approaching. This is because the Doppler effect causes a shift towards shorter wavelengths (blueshift) when the source of the light is moving towards the observer. Therefore, if the light from a star is blueshifted, it means that the star is moving towards us.
46.
Resonance occurs at __________ frequencies.
Correct Answer
natural
characteristic
Explanation
Resonance occurs at natural and characteristic frequencies. Resonance is the phenomenon in which an object or system vibrates with maximum amplitude at its natural frequency. The natural frequency is the frequency at which an object naturally oscillates without any external force. On the other hand, the characteristic frequency is the frequency at which a system naturally resonates due to its specific properties. Therefore, both natural and characteristic frequencies are associated with resonance.