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Q1. Sound waves are mechanical because they
Sound waves are called mechanical waves because they require a material medium (solid, liquid, or gas) to travel. They cannot travel through a vacuum because there are no particles to vibrate and carry the wave. Sound is not visible, does not travel in vacuum, and is longitudinal, not transverse.
Q2. Sound reaches our ear because
Sound reaches our ear because the disturbance (wave) travels through the medium and reaches our ear. The particles of the medium do not travel to the ear; they only vibrate about their mean positions and pass the disturbance along. The medium itself does not move forward; only the disturbance moves.
Q3. Sound waves are called mechanical waves because they
Sound waves are called mechanical waves because they need a material medium (solid, liquid, or gas) to propagate. Mechanical waves require particles to vibrate and transfer energy. Sound does not carry mass, does not primarily produce heat, and its speed depends on the medium.
Q4. Pressure in a medium depends on
Pressure in a medium depends on the number of particles per unit volume (density). More particles in a given volume means more collisions and higher pressure. Temperature can affect pressure, but the direct factor is the density of particles. Colour and shape do not affect pressure.
Q5. Sound can be visualised as a wave because
Sound can be visualised as a wave because it involves the propagation of a disturbance through a medium. A wave is a disturbance that travels from one point to another, transferring energy. Sound does not produce light, primarily transfer heat, or rely on reflection to be a wave.
Q6. In longitudinal waves, particles move
In longitudinal waves, particles vibrate parallel to the direction of wave propagation. This back-and-forth motion creates compressions and rarefactions. Transverse waves have particles moving perpendicular to the wave direction. Sound waves in air are longitudinal.
Q7. Rarefaction corresponds to
Rarefaction is a region in a longitudinal wave where the density of particles is minimum. Particles are spread apart, creating a region of low pressure. Compression corresponds to maximum density, and there is never “no density” in a medium.
Q8. The direction of particle vibration in sound waves is
In sound waves, particles vibrate parallel to the direction of wave propagation. This is why sound waves are classified as longitudinal waves. Perpendicular vibration is characteristic of transverse waves. Diagonal and circular motions are not typical for sound waves.
Q9. In sound waves, each particle
In sound waves, each particle vibrates and pushes the next particle, transferring the disturbance. The particles do not disappear, stop permanently, or move to the ear. They oscillate about their mean positions and pass energy to neighbouring particles.
Q10. The correct sequence in sound propagation is
Sound propagation follows this sequence: first, a vibrating object creates a disturbance in the medium; this disturbance travels as a wave and eventually reaches the ear, where it is detected. Heat and pressure are not the initial steps, the medium does not move, and particles do not flow.
Q11. Sound cannot travel through
Sound cannot travel through a vacuum because there are no particles to vibrate and carry the wave. Steel, water, and air are all material media that allow sound to travel. Sound travels fastest in solids like steel, slower in liquids, and slowest in gases.
Q12. Sound propagation can be seen as propagation of
Sound propagation can be seen as propagation of pressure variations through a medium. Sound waves consist of alternating regions of high pressure (compressions) and low pressure (rarefactions). These pressure variations travel through the medium, carrying energy.
Q13. In sound waves, particles
In sound waves, particles oscillate back and forth about their mean positions. They do not remain fixed, move upward only, or travel with the wave. The particles vibrate and transfer energy to neighbouring particles, but they do not move permanently in the direction of the wave.
Q14. Compression is a region of
Compression is a region of high pressure where particles are crowded together. This occurs when the vibrating object moves forward, pushing particles closer. Rarefaction is a region of low pressure. Compression has high pressure, not constant, low, or no pressure.
Q15. The slinky dot moves
In a slinky demonstration of sound waves, the dot on the slinky moves back and forth about its mean position. This represents the vibration of particles in a longitudinal wave. The dot does not move in circles, permanently forward, or randomly.
Q16. Which statement is correct?
Sound is a mechanical wave because it requires a material medium to travel. It is not electromagnetic; electromagnetic waves (like light) can travel in vacuum. Particles do not move long distances; they vibrate about their mean positions. Sound cannot travel in vacuum.
Q17. Rarefaction is a region of
Rarefaction is a region of low pressure because particles are spread apart. The density is minimum, and pressure is low. High pressure and high density are characteristics of compression. Rarefaction is the opposite of compression.
Q18. The movement of disturbance in sound is due to
The movement of disturbance in sound is due to energy transfer. The vibrating source creates energy that is transferred from particle to particle through the medium. The medium itself does not move, and particles do not travel. Energy is what propagates as a wave.
Q19. If all air is removed from the bell jar, the sound will
If all air is removed from the bell jar, creating a vacuum, the sound will not be heard. Sound requires a medium to travel, and without air, there are no particles to carry the sound waves. The bell may still vibrate, but the sound cannot reach our ears through a vacuum.
Q20. In sound propagation, the particles of the medium
In sound propagation, the particles of the medium oscillate about their mean positions. They do not travel to the ear, move forward permanently, or remain completely still. The vibration of particles transfers energy without the net movement of the particles themselves.
Q21. Water surface waves produced by a pebble are
Water surface waves produced by a pebble are transverse waves. The particles of water move up and down (perpendicular to the direction of wave propagation). This is different from sound waves, which are longitudinal. Water waves are mechanical but transverse in nature.
Q22. Which of the following is the most common medium for sound?
Air is the most common medium for sound because we live in air and most sounds we hear travel through air. Sound can also travel through steel, water, and glass, but air is the medium we encounter most frequently in daily life.
Q23. In longitudinal waves, compressions and rarefactions are formed due to
In longitudinal waves, compressions and rarefactions are formed due to pressure changes. When particles are pushed together, pressure increases (compression); when they are spread apart, pressure decreases (rarefaction). Shape, colour, and temperature changes are not involved.
Q24. Sound waves in air are
Sound waves in air are longitudinal waves. The particles of air vibrate parallel to the direction of wave propagation, creating compressions and rarefactions. Sound is not transverse, standing (in most cases), or circular in air.
Q25. More density of particles in a region means
More density of particles in a region means more pressure because there are more particles colliding. In a compression, density is high and pressure is high. In a rarefaction, density is low and pressure is low. Vacuum has no particles.
Q26. Transverse waves differ from longitudinal waves because
Transverse waves differ from longitudinal waves because particles move perpendicular to the direction of wave propagation. In longitudinal waves, particles move parallel. Both types need a medium, but sound is longitudinal, and light is electromagnetic (does not need a medium).
Q27. When a vibrating object moves forward, it produces
When a vibrating object moves forward, it pushes the particles in front of it, creating a region of high pressure called compression. When it moves backward, it creates a rarefaction. Vacuum and echo are different phenomena.
Q28. Sound waves do not transport
Sound waves do not transport particles. They transport energy, disturbance, and pressure variations. The particles of the medium vibrate about their mean positions but do not travel with the wave. Energy is what is carried by the sound wave.
Q29. Light is not a mechanical wave because
Light is not a mechanical wave because it does not need a medium to travel. Light is an electromagnetic wave that can travel through a vacuum. Mechanical waves like sound require a material medium. Light does produce heat and has energy, but that is not why it is not mechanical.
Q30. A sound wave in air consists of
A sound wave in air consists of alternating compressions (high pressure) and rarefactions (low pressure). These regions are formed due to the vibrations of air particles. Sound does not consist of heat, light, reflections, or matter. It is a mechanical wave made of pressure variations.
Q31. Compression corresponds to
Compression corresponds to high density because particles are crowded together. This region has high pressure. Rarefaction corresponds to low density. Zero particles and no pressure do not exist in a medium.
Q32. On the moon, sound cannot be heard because
On the moon, sound cannot be heard because there is no air (or any atmosphere) to carry the sound waves. Sound requires a medium to travel. Vibration still occurs, but without a medium, the sound cannot propagate. Gravity and temperature are not the direct reasons.
Q33. The propagation of sound involves
The propagation of sound involves density variations in the medium. As sound passes through, particles are alternately compressed (high density) and rarefied (low density). These density variations travel as a wave. Heat flow, light reflection, and colour changes are not involved.
Q34. As air is removed from the bell jar, the sound becomes faint because
As air is removed from the bell jar, the sound becomes faint because the medium (air) for sound to travel decreases. With fewer particles to vibrate and carry the sound, the intensity decreases. The bell still vibrates, but the sound cannot travel effectively without a medium.
Q35. The bell jar experiment proves that
The bell jar experiment proves that sound needs a medium to travel. When air is removed from the jar, the sound becomes faint and eventually inaudible, even though the bell continues to vibrate. This shows that sound cannot travel through a vacuum.
Q36. Sound produced by a school bell is due to
Sound produced by a school bell is due to the vibration of the bell. When the bell is struck, it vibrates, creating sound waves in the surrounding air. Air pressure, light emission, and heating of air are not the direct causes of sound production.
Q37. Sound waves require a medium because
Sound waves require a medium because they involve particle vibrations. The sound wave propagates through the vibration of particles in the medium. Without particles, there can be no vibration to carry the wave. Sound does not primarily produce heat, reflect light, or depend on speed in this context.
Q38. The energy of sound moves due to
The energy of sound moves due to wave motion. The disturbance (wave) travels through the medium, carrying energy from the source to the receiver. Particles do not transport energy; they vibrate and pass it along. Medium movement and airflow are not the correct descriptions.
Q39. Sound propagation in air is
Sound propagation in air is mechanical because it requires a material medium (air) to travel. Mechanical waves transfer energy through particle vibrations. Sound is not optical (light), electromagnetic (light), or thermal (heat) in nature.
Q40. A wave is defined as
A wave is defined as a disturbance that moves through a medium, transferring energy from one point to another without the net transfer of matter. Sound is a wave because it is a disturbance that propagates through a medium. The other options do not correctly define a wave.
Q41. An example of a transverse wave is
Light is an example of a transverse wave. In transverse waves, particles (or fields) vibrate perpendicular to the direction of wave propagation. Ultrasound, sound in air, and sound in water are all longitudinal waves. Light is electromagnetic and transverse.
Q42. The slinky experiment demonstrates
The slinky experiment demonstrates longitudinal waves. When a slinky is pushed and pulled, compressions and rarefactions move along it, similar to sound waves. This experiment helps visualize how sound waves travel through a medium.
Q43. Sound waves carry
Sound waves carry energy from the source to the receiver. They do not carry particles, matter, or the medium itself. The particles vibrate and transfer energy to neighbouring particles, but the wave itself is the movement of energy.
Q44. Which of the following is NOT a mechanical wave?
Light is NOT a mechanical wave. It is an electromagnetic wave that does not require a medium to travel. Sound, water waves, and slinky waves are all mechanical waves because they require a material medium. Light can travel through a vacuum.
Q45. In transverse waves, particles oscillate
In transverse waves, particles oscillate perpendicular to the direction of wave propagation. This can be up and down (or side to side). In longitudinal waves, particles oscillate along the wave direction. Forward only, circles, and along wave direction are not correct.
Q46. Which wave needs a medium to travel?
Sound waves need a medium to travel because they are mechanical waves. X-rays, radio waves, and light waves are all electromagnetic waves and do not require a medium. Sound is the only mechanical wave among the options.
Q47. Sound waves are classified as
Sound waves are classified as longitudinal waves because the particles of the medium vibrate parallel to the direction of wave propagation. This creates compressions and rarefactions. Standing, surface, and transverse waves are different types of waves.
Q48. In the bell jar experiment, the bell continues vibrating but sound fades because
In the bell jar experiment, the bell continues vibrating but the sound fades because the medium (air) is being removed. As the air is pumped out, there are fewer particles to carry the sound, so the sound becomes fainter and eventually stops. The vibration continues, but the medium is insufficient for propagation.
Q49. During the propagation of sound, what actually travels through the medium?
During the propagation of sound, the disturbance (wave) actually travels through the medium. Energy is also transferred, but it is the disturbance that moves forward. The medium itself does not travel, and particles do not travel long distances. The disturbance is what propagates.
Q50. The disturbance in sound waves moves because
The disturbance in sound waves moves because particles push their neighbours. As each particle vibrates, it transfers energy to the next particle, propagating the disturbance forward. Particles do not flow, pressure does not stop, and the medium does not shift permanently. This chain of particle interactions is how sound travels.