All Exams >
Class 8 >
Science Olympiad Class 8 >
All Questions
All questions of Sound for Class 8 Exam
The length of vocal cords of a man is about
- a)5 mm
- b)10 mm
- c)15 mm
- d)17 - 25 mm
Correct answer is option 'D'. Can you explain this answer?
The length of vocal cords of a man is about
a)
5 mm
b)
10 mm
c)
15 mm
d)
17 - 25 mm
|
Sanjit Nigam answered |
The length of vocal cords of women are 5mm and the length of vocal cords of men are 20mm. Therefore, men have a deep and low pitched voice and women have a high pitched voice.
Therefore, option (d) is correct
Therefore, option (d) is correct
The audible range of sound frequencies for human beings is- a)0Hz – 20Hz
- b)20Hz – 2000Hz
- c)50Hz – 5000Hz
- d)20Hz – 20,000Hz
Correct answer is option 'D'. Can you explain this answer?
The audible range of sound frequencies for human beings is
a)
0Hz – 20Hz
b)
20Hz – 2000Hz
c)
50Hz – 5000Hz
d)
20Hz – 20,000Hz
|
Maya Nambiar answered |
The audible range of sound frequencies for human beings is 20Hz – 20,000Hz. This range is the range of frequencies that humans can hear. The lower end of the range, 20Hz, is the lowest frequency that humans can hear, while the upper end of the range, 20,000Hz, is the highest frequency that humans can hear.
The quality of two sounds with the same fundamental frequency differs because of the number and relative loudness of the _____- a)sound
- b)harmonics
- c)pitch
- d)none of these
Correct answer is option 'B'. Can you explain this answer?
The quality of two sounds with the same fundamental frequency differs because of the number and relative loudness of the _____
a)
sound
b)
harmonics
c)
pitch
d)
none of these
|
Mrinalini Chakraborty answered |
Quality of Sounds with the Same Fundamental Frequency
Introduction:
The quality of a sound refers to its unique characteristics that allow us to distinguish different sounds, even if they have the same fundamental frequency. Two sounds with the same fundamental frequency can have different qualities due to the number and relative loudness of their harmonics.
Fundamental Frequency:
The fundamental frequency is the lowest frequency component of a complex sound. It determines the pitch of the sound and is the frequency at which an object or medium vibrates naturally. For example, the fundamental frequency of a guitar string is determined by its length, tension, and mass per unit length.
Harmonics:
Harmonics are multiples of the fundamental frequency that contribute to the overall sound quality. When an object vibrates, it produces not only the fundamental frequency but also higher-frequency components called harmonics. These harmonics are usually integer multiples of the fundamental frequency. For example, if the fundamental frequency is 100 Hz, the first harmonic would be 200 Hz, the second harmonic would be 300 Hz, and so on.
Number of Harmonics:
The number of harmonics present in a sound determines its richness or timbre. A sound with a larger number of harmonics will have a more complex timbre and will sound richer. This is because the additional harmonics add different frequencies and amplitudes to the sound, creating a more intricate waveform. In contrast, a sound with fewer harmonics will sound simpler and less rich.
Relative Loudness of Harmonics:
The relative loudness of harmonics refers to the amplitude or intensity of each harmonic compared to the fundamental frequency. The amplitudes of the harmonics can vary, and this variation contributes to the overall quality of the sound. If certain harmonics are louder or softer than others, it can significantly affect the perception of the sound. For example, a sound with dominant higher-order harmonics may sound brighter, while a sound with dominant lower-order harmonics may sound darker.
Conclusion:
In summary, the quality of two sounds with the same fundamental frequency can differ due to the number and relative loudness of their harmonics. The number of harmonics determines the richness or complexity of the sound, while the relative loudness of harmonics affects the overall perception of the sound. By manipulating the number and loudness of harmonics, we can create sounds with different qualities, even if they share the same fundamental frequency.
Introduction:
The quality of a sound refers to its unique characteristics that allow us to distinguish different sounds, even if they have the same fundamental frequency. Two sounds with the same fundamental frequency can have different qualities due to the number and relative loudness of their harmonics.
Fundamental Frequency:
The fundamental frequency is the lowest frequency component of a complex sound. It determines the pitch of the sound and is the frequency at which an object or medium vibrates naturally. For example, the fundamental frequency of a guitar string is determined by its length, tension, and mass per unit length.
Harmonics:
Harmonics are multiples of the fundamental frequency that contribute to the overall sound quality. When an object vibrates, it produces not only the fundamental frequency but also higher-frequency components called harmonics. These harmonics are usually integer multiples of the fundamental frequency. For example, if the fundamental frequency is 100 Hz, the first harmonic would be 200 Hz, the second harmonic would be 300 Hz, and so on.
Number of Harmonics:
The number of harmonics present in a sound determines its richness or timbre. A sound with a larger number of harmonics will have a more complex timbre and will sound richer. This is because the additional harmonics add different frequencies and amplitudes to the sound, creating a more intricate waveform. In contrast, a sound with fewer harmonics will sound simpler and less rich.
Relative Loudness of Harmonics:
The relative loudness of harmonics refers to the amplitude or intensity of each harmonic compared to the fundamental frequency. The amplitudes of the harmonics can vary, and this variation contributes to the overall quality of the sound. If certain harmonics are louder or softer than others, it can significantly affect the perception of the sound. For example, a sound with dominant higher-order harmonics may sound brighter, while a sound with dominant lower-order harmonics may sound darker.
Conclusion:
In summary, the quality of two sounds with the same fundamental frequency can differ due to the number and relative loudness of their harmonics. The number of harmonics determines the richness or complexity of the sound, while the relative loudness of harmonics affects the overall perception of the sound. By manipulating the number and loudness of harmonics, we can create sounds with different qualities, even if they share the same fundamental frequency.
Which surface absorbs sound better?- a)hard
- b)smooth
- c)slippery
- d)soft
Correct answer is option 'D'. Can you explain this answer?
Which surface absorbs sound better?
a)
hard
b)
smooth
c)
slippery
d)
soft
|
Srestha Nambiar answered |
Soft surfaces absorb sound better
Soft surfaces are more effective at absorbing sound compared to hard, smooth, or slippery surfaces. This is due to the following reasons:
1. Porous structure:
Soft materials such as foam, fabric, or carpet have a porous structure that allows sound waves to penetrate and get trapped within the material. This absorption process reduces the reflection of sound waves, thus dampening the overall noise levels in a space.
2. Energy dissipation:
When sound waves hit a soft surface, the energy is dissipated as it causes the material to vibrate. This vibration converts the acoustic energy into small amounts of heat, reducing the intensity of the sound.
3. Thickness:
Soft surfaces tend to be thicker than hard surfaces, providing more material for sound waves to travel through and be absorbed. This thickness helps in increasing the absorption capabilities of the surface.
4. Surface texture:
Soft surfaces often have irregular textures that help scatter sound waves, preventing them from reflecting back into the environment. This scattering effect further contributes to sound absorption.
In conclusion, soft surfaces are preferred for sound absorption due to their porous structure, energy dissipation properties, thickness, and surface texture. Using soft materials in environments where noise reduction is important can help create a more acoustically comfortable space.
Human being can hear two sounds separately and distinctly if they are separated by a time interval of _____ second(s).- a)0.1
- b)0.01
- c)1
- d)10
Correct answer is option 'A'. Can you explain this answer?
Human being can hear two sounds separately and distinctly if they are separated by a time interval of _____ second(s).
a)
0.1
b)
0.01
c)
1
d)
10
|
|
Maya Nambiar answered |
The correct answer is "0.1 second(s)."
The ability of the human ear to distinguish between two separate and distinct sounds is called temporal resolution, and it is influenced by a variety of factors, including the intensity and frequency of the sounds. The minimum time interval that is required for the human ear to distinguish between two separate and distinct sounds is called the temporal resolution threshold.
Studies have shown that the temporal resolution threshold for most people is around 0.1 seconds. This means that if two sounds are separated by a time interval of at least 0.1 seconds, most people will be able to hear them as distinct, separate sounds. If the time interval between the two sounds is shorter than 0.1 seconds, they may be perceived as a single sound rather than two separate sounds.
It is worth noting that temporal resolution can vary from person to person and can also be influenced by factors such as age, hearing loss, and the specific characteristics of the sounds being heard.
Sound is produced by a- a)moving object
- b)stationary object
- c)vibrating object
- d)rotating object
Correct answer is option 'C'. Can you explain this answer?
Sound is produced by a
a)
moving object
b)
stationary object
c)
vibrating object
d)
rotating object
|
C K Academy answered |
Why is sound produced by a vibrating object?
- Vibrations create sound: When an object vibrates, it creates disturbances in the air molecules around it. These disturbances travel through the air in the form of sound waves.
- Frequency of vibrations: The frequency of the vibrations determines the pitch of the sound produced. Higher frequency vibrations create higher pitched sounds, while lower frequency vibrations create lower pitched sounds.
- Amplitude of vibrations: The amplitude of the vibrations determines the volume of the sound produced. Greater amplitude creates louder sounds, while smaller amplitude creates softer sounds.
- Human ear: The human ear is sensitive to these sound waves and can detect them as audible sounds. The ear converts these sound waves into electrical signals that are interpreted by the brain as sound.
- Examples of vibrating objects: Some common examples of vibrating objects that produce sound include musical instruments, vocal cords, and speakers.
The speed of sound in air is- a)331 m/s
- b)665 m/s
- c)1550 m/s
- d)173 m/s
Correct answer is option 'A'. Can you explain this answer?
The speed of sound in air is
a)
331 m/s
b)
665 m/s
c)
1550 m/s
d)
173 m/s
|
|
Maya Nambiar answered |
The speed of sound in air is the speed at which sound waves travel through the air. This speed is determined by the temperature, pressure, and humidity of the air. At sea level and at a temperature of 15degree C, the speed of sound in air is approximately 331 m/s. This is the most commonly accepted value for the speed of sound in air.
An object vibrates with a frequency of 15 Hz. Which of the following is true?- a)It produces sound which we can hear if we strain our ears.
- b)It produces sound which we can hear.
- c)It produces sound which we cannot hear.
- d)It does not produce a sound.
Correct answer is option 'C'. Can you explain this answer?
An object vibrates with a frequency of 15 Hz. Which of the following is true?
a)
It produces sound which we can hear if we strain our ears.
b)
It produces sound which we can hear.
c)
It produces sound which we cannot hear.
d)
It does not produce a sound.
|
Aditi Saxena answered |
It produces sound that we cannot hear because Humans can hear sounds in the frequency range 20Hz - 20000Hz.
So, Option c is correct answer.
Shrillness of the sound is determined by the ____ of vibration.- a)amplitude
- b)frequency
- c)Noise
- d)oscillation
Correct answer is option 'B'. Can you explain this answer?
Shrillness of the sound is determined by the ____ of vibration.
a)
amplitude
b)
frequency
c)
Noise
d)
oscillation
|
|
Aditi Saxena answered |
The shrillness of a sound is determined by its frequency, which is the number of vibrations per second. The higher the frequency, the higher the pitch of the sound. The lower the frequency, the lower the pitch of the sound.
The quality of sound produced by a tuning fork is different from that produced by a musical instrument because of the difference in- a)frequency
- b)harmonics
- c)amplitude
- d)none of these
Correct answer is option 'B'. Can you explain this answer?
The quality of sound produced by a tuning fork is different from that produced by a musical instrument because of the difference in
a)
frequency
b)
harmonics
c)
amplitude
d)
none of these
|
Ritika Saha answered |
The correct answer is option B: harmonics.
Explanation:
When comparing the sound produced by a tuning fork and a musical instrument, there are several factors that contribute to the difference in quality of sound. However, the most significant factor is the difference in harmonics.
1. What are harmonics?
Harmonics are the additional frequencies produced alongside the fundamental frequency of a sound. They are the multiples of the fundamental frequency and are responsible for the unique timbre or quality of the sound.
2. Tuning fork:
A tuning fork is a simple musical instrument consisting of a metal rod with two prongs. When struck, it vibrates at a specific frequency determined by its size and shape. The sound produced by a tuning fork contains primarily the fundamental frequency and very few harmonics. This results in a pure, simple, and clear sound.
3. Musical instrument:
On the other hand, a musical instrument such as a guitar, piano, or flute, produces a complex sound with a wide range of harmonics. The harmonics in the sound produced by these instruments give them their characteristic timbre and make the sound more rich and complex compared to the tuning fork.
4. Importance of harmonics in sound quality:
The presence and arrangement of harmonics greatly affect the perceived quality of sound. Different musical instruments have unique harmonic structures, which are determined by their design and the way they produce sound. These harmonic structures contribute to the richness, complexity, and unique tone of each instrument.
5. Frequency and amplitude:
While frequency (a) and amplitude (c) are important factors in sound production, they do not solely account for the difference in sound quality between a tuning fork and a musical instrument. Frequency refers to the number of vibrations per second, while amplitude refers to the strength or intensity of the sound wave. While these factors contribute to the overall sound characteristics, they do not differentiate the sound produced by a tuning fork and a musical instrument as significantly as the presence and arrangement of harmonics.
In conclusion, the quality of sound produced by a tuning fork is different from that produced by a musical instrument primarily due to the difference in harmonics. The tuning fork produces a pure, simple sound with few harmonics, while musical instruments produce a more complex sound with a wider range of harmonics, resulting in their characteristic timbre and richness.
Explanation:
When comparing the sound produced by a tuning fork and a musical instrument, there are several factors that contribute to the difference in quality of sound. However, the most significant factor is the difference in harmonics.
1. What are harmonics?
Harmonics are the additional frequencies produced alongside the fundamental frequency of a sound. They are the multiples of the fundamental frequency and are responsible for the unique timbre or quality of the sound.
2. Tuning fork:
A tuning fork is a simple musical instrument consisting of a metal rod with two prongs. When struck, it vibrates at a specific frequency determined by its size and shape. The sound produced by a tuning fork contains primarily the fundamental frequency and very few harmonics. This results in a pure, simple, and clear sound.
3. Musical instrument:
On the other hand, a musical instrument such as a guitar, piano, or flute, produces a complex sound with a wide range of harmonics. The harmonics in the sound produced by these instruments give them their characteristic timbre and make the sound more rich and complex compared to the tuning fork.
4. Importance of harmonics in sound quality:
The presence and arrangement of harmonics greatly affect the perceived quality of sound. Different musical instruments have unique harmonic structures, which are determined by their design and the way they produce sound. These harmonic structures contribute to the richness, complexity, and unique tone of each instrument.
5. Frequency and amplitude:
While frequency (a) and amplitude (c) are important factors in sound production, they do not solely account for the difference in sound quality between a tuning fork and a musical instrument. Frequency refers to the number of vibrations per second, while amplitude refers to the strength or intensity of the sound wave. While these factors contribute to the overall sound characteristics, they do not differentiate the sound produced by a tuning fork and a musical instrument as significantly as the presence and arrangement of harmonics.
In conclusion, the quality of sound produced by a tuning fork is different from that produced by a musical instrument primarily due to the difference in harmonics. The tuning fork produces a pure, simple sound with few harmonics, while musical instruments produce a more complex sound with a wider range of harmonics, resulting in their characteristic timbre and richness.
Sound travels faster in solids than in gases because- a)sound is a form of energy
- b)sound bounces back when reflected to a solid
- c)sound cannot travel in gases smoothly
- d)molecules of solids are closely packed as compared to gases
Correct answer is option 'D'. Can you explain this answer?
Sound travels faster in solids than in gases because
a)
sound is a form of energy
b)
sound bounces back when reflected to a solid
c)
sound cannot travel in gases smoothly
d)
molecules of solids are closely packed as compared to gases
|
Ashwini Mehra answered |
Explanation:
Sound is a form of mechanical energy that travels through a medium in the form of waves. The speed of sound depends on the properties of the medium through which it travels. Solids, liquids, and gases are all mediums through which sound can travel, but sound travels faster in solids compared to gases. This can be explained by the following factors:
Molecular Arrangement:
In solids, the molecules are tightly packed and closely arranged in a regular pattern. This close arrangement allows sound waves to easily pass from one molecule to another, transmitting the energy faster. On the other hand, in gases, the molecules are far apart and move randomly. This random motion hinders the transmission of sound waves, resulting in slower sound propagation.
Elasticity:
Another factor that affects the speed of sound is the elasticity of the medium. Solids have a higher degree of elasticity compared to gases. When a sound wave passes through a solid, the molecules vibrate and return to their original position quickly due to the strong intermolecular forces. This elastic behavior allows the sound wave to propagate faster. In gases, however, the molecules have weaker intermolecular forces and take longer to return to their original position, leading to slower sound propagation.
Density:
The density of the medium also plays a role in the speed of sound. Solids have a higher density compared to gases. The denser the medium, the closer the molecules are to each other, allowing sound waves to travel faster. In gases, the low density and large gaps between molecules hinder the transmission of sound waves, resulting in slower speed.
Conclusion:
In conclusion, sound travels faster in solids compared to gases because of the closely packed molecular arrangement, higher degree of elasticity, and higher density of solids. These factors enable sound waves to propagate more efficiently through solids, while gases with their random molecular motion and low density tend to slow down the transmission of sound.
Sound is a form of mechanical energy that travels through a medium in the form of waves. The speed of sound depends on the properties of the medium through which it travels. Solids, liquids, and gases are all mediums through which sound can travel, but sound travels faster in solids compared to gases. This can be explained by the following factors:
Molecular Arrangement:
In solids, the molecules are tightly packed and closely arranged in a regular pattern. This close arrangement allows sound waves to easily pass from one molecule to another, transmitting the energy faster. On the other hand, in gases, the molecules are far apart and move randomly. This random motion hinders the transmission of sound waves, resulting in slower sound propagation.
Elasticity:
Another factor that affects the speed of sound is the elasticity of the medium. Solids have a higher degree of elasticity compared to gases. When a sound wave passes through a solid, the molecules vibrate and return to their original position quickly due to the strong intermolecular forces. This elastic behavior allows the sound wave to propagate faster. In gases, however, the molecules have weaker intermolecular forces and take longer to return to their original position, leading to slower sound propagation.
Density:
The density of the medium also plays a role in the speed of sound. Solids have a higher density compared to gases. The denser the medium, the closer the molecules are to each other, allowing sound waves to travel faster. In gases, the low density and large gaps between molecules hinder the transmission of sound waves, resulting in slower speed.
Conclusion:
In conclusion, sound travels faster in solids compared to gases because of the closely packed molecular arrangement, higher degree of elasticity, and higher density of solids. These factors enable sound waves to propagate more efficiently through solids, while gases with their random molecular motion and low density tend to slow down the transmission of sound.
In stringed instruments, frequency of sound produced depends on- a)tightness of string
- b)length of string
- c)thickness of string
- d)all of the above
Correct answer is option 'D'. Can you explain this answer?
In stringed instruments, frequency of sound produced depends on
a)
tightness of string
b)
length of string
c)
thickness of string
d)
all of the above
|
EduRev Class 8 answered |
The frequency of sound produced by a stringed instrument depends on:
- Tightness (Tension) of the string – Higher tension increases frequency (pitch).
- Length of the string – Shorter strings produce higher frequencies.
- Thickness (Mass per unit length) of the string – Thicker strings vibrate slower, producing lower frequencies.
Thus, all three factors (a, b, and c) affect the frequency.Final Answer: (d) all of the above
In our ears, the vibrations in the air are picked up by which ear?- a)inner ear
- b)outer ear
- c)middle ear
- d)none of these
Correct answer is option 'B'. Can you explain this answer?
In our ears, the vibrations in the air are picked up by which ear?
a)
inner ear
b)
outer ear
c)
middle ear
d)
none of these
|
Trisha Vashisht answered |
The outer ear (which includes the visible ear and ear canal) is the part that collects sound waves from the air. These sound waves then travel through the ear canal to the middle ear, where they cause the eardrum to vibrate. Afterward, the vibrations are transmitted to the inner ear, specifically to the cochlea, where they are converted into nerve signals that the brain interprets as sound.
So, the outer ear starts the process of picking up sound vibrations.
Prolonged exposure to noise louder than ____ can lead to permanent hearing damage.- a)70dB
- b)17dB
- c)7dB
- d)700dB
Correct answer is option 'A'. Can you explain this answer?
Prolonged exposure to noise louder than ____ can lead to permanent hearing damage.
a)
70dB
b)
17dB
c)
7dB
d)
700dB
|
Malavika Chopra answered |
Explanation:
Noise-induced hearing loss is a major concern in today's world due to the increasing levels of noise pollution. Prolonged exposure to noise levels above 70dB can lead to permanent damage to the delicate hair cells in the inner ear, which are responsible for transmitting sound signals to the brain.
Effects of Noise Exposure:
- Exposure to noise levels above 70dB for extended periods can cause temporary hearing loss, tinnitus (ringing in the ears), and ear pain.
- Continued exposure to loud noise can lead to permanent damage to the hair cells in the inner ear, resulting in irreversible hearing loss.
- Noise-induced hearing loss is cumulative, meaning that the more time you spend in a noisy environment, the greater the risk of damage to your hearing.
Prevention of Hearing Damage:
- Use ear protection such as earplugs or earmuffs when exposed to loud noise levels.
- Take breaks from noisy environments to give your ears a rest.
- Keep the volume of personal listening devices such as headphones and earphones at a safe level.
- Avoid prolonged exposure to loud noises, especially in settings such as concerts, construction sites, and nightclubs.
In conclusion, it is essential to protect your hearing by being mindful of your exposure to loud noises and taking preventive measures to avoid permanent hearing damage. Noise levels above 70dB should be a signal to take necessary precautions to safeguard your hearing health.
Sounds whose frequencies are greater than 20,000 Hz are called- a)infrasonic sounds
- b)ultrasonic sound
- c)supersonic sound
- d)none of these
Correct answer is option 'B'. Can you explain this answer?
Sounds whose frequencies are greater than 20,000 Hz are called
a)
infrasonic sounds
b)
ultrasonic sound
c)
supersonic sound
d)
none of these
|
|
Mainak Sharma answered |
Ultrasonic Sound Explanation:
- Definition: Sounds whose frequencies are greater than 20,000 Hz are called ultrasonic sounds.
- Frequencies: Ultrasonic sounds have frequencies higher than the upper limit of human hearing, which is typically around 20,000 Hz.
- Applications: Ultrasonic sound waves have various practical applications such as in medical imaging (ultrasound scans), cleaning, welding, and even pest control.
- Animal Communication: Some animals, like bats and dolphins, use ultrasonic sounds for communication and navigation purposes.
- Human Perception: While humans cannot hear ultrasonic sounds, some individuals may perceive them indirectly through effects like interference patterns or pressure waves.
The to - and - fro motion of a body about its mean position is called- a)Oscillation
- b)Linear motion
- c)Fluctuation
- d)Rotation
Correct answer is option 'A'. Can you explain this answer?
The to - and - fro motion of a body about its mean position is called
a)
Oscillation
b)
Linear motion
c)
Fluctuation
d)
Rotation
|
|
Trisha Vashisht answered |
The to-and-fro motion of a body about its mean position can be described as "oscillation".
Chapter doubts & questions for Sound - Science Olympiad Class 8 2025 is part of Class 8 exam preparation. The chapters have been prepared according to the Class 8 exam syllabus. The Chapter doubts & questions, notes, tests & MCQs are made for Class 8 2025 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests here.
Chapter doubts & questions of Sound - Science Olympiad Class 8 in English & Hindi are available as part of Class 8 exam.
Download more important topics, notes, lectures and mock test series for Class 8 Exam by signing up for free.
Science Olympiad Class 8
70 videos|132 docs|67 tests
|
|
© EduRev
|
Education Revolution
|
|
Signup on EduRev and stay on top of your study goals
10M+ students crushing their study goals daily