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Which property of sound waves is primarily responsible for the phenomenon of echo in a large empty hall?
Refraction
Reflection
Diffraction
Polarization
Reflection
An echo is a distinct sound produced by the reflection of sound waves from a distant surface. For the human ear to distinguish the original sound and the reflected sound, there must be a minimum time interval of approximately 0.1 seconds.
An echo is a distinct sound produced by the reflection of sound waves from a distant surface. For the human ear to distinguish the original sound and the reflected sound, there must be a minimum time interval of approximately 0.1 seconds.
Think of an echo like throwing a rubber ball against a hard wall; just as the ball bounces back to you after hitting the surface, sound waves bounce back to your ears.
SER: Sound Echo Reflection
d=2v├ЧtтАЛ тАФ where d is the distance to the reflecting surface, v is the velocity of sound, and t is the time delay.
v=f╬╗ тАФ where v is the wave velocity, f is frequency, and ╬╗ is wavelength.
When sound waves encounter a hard surface like a wall or cliff, they undergo reflection according to the laws of reflection. Given the speed of sound in air is approximately 344┬аm/s, the minimum distance required to perceive an echo is 2344├Ч0.1тАЛ=17.2┬аmeters. If the distance is less than this, the reflected sound merges with the original sound, causing persistence of hearing rather than a distinct echo.
Echo requires a minimum distance of approximately 17.2 meters in air at 20┬░C.
Hard surfaces like concrete or stone are better reflectors than soft materials like curtains, which absorb sound.
The phenomenon is based on the law of reflection: the angle of incidence equals the angle of reflection.
Used in SONAR to measure depth of the ocean floor.
Used in medical ultrasonography for internal body imaging.
Reverberation in poorly designed halls can cause garbled sound.
Excessive echo interferes with speech clarity in auditoriums.
SONAR (Sound Navigation and Ranging)
Stethoscope echo-based diagnostic tools
The persistence of human hearing lasts for about 0.1 seconds.
Refraction refers to the bending of waves, Diffraction refers to the spreading of waves around obstacles, and Polarization is unique to transverse waves (sound is longitudinal).
B is correct тАФ An echo is formed due to the reflection of sound waves off an obstacle.
Always remember that sound is a longitudinal mechanical wave and cannot be polarized, unlike light which is a transverse electromagnetic wave.
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