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10:04 AM | 8.8KB/s Z --- rT, sound.pdf - Read-only, , co, , , , Frequency: Number of oscillations of sound waves is called its frequency. The number, of peak and troughs per unit of time will give frequency. It is represented by v (nu) and, its SI unit is Hertz (Hz)., , Time Period: The time taken to complete one oscillation is called its time period. Its unit, is second and is represented by T., , Relation of frequency and time period:, , V=W/T, , Amplitude: The magnitude of the maximum disturbance in the medium on either side of, the mean value is called the amplitude of the wave. It is usually represented by the letter, A. Its unit is meter., , Softness or Loudness of Sound: If the amplitude is smaller then the sound will be softer, and if it is larger then sound will be louder. Higher amplitude helps the sound wave is, travelling faster., , Speed of sound: It is the distance which compression or a rarefaction travels per unit of, time., , Sound-cbse-notes-class-9-science-4, So, Speed = Wavelength Frequency, , The speed of the sound remains almost the same for all frequencies in a given medium, under the same physical condition., , Speed of Sound in Different Media at 25° C., , Reflection of Sound: Sound reflects off a surface in the same way as light reflects and, follows same rules of reflection. The incident sound and the reflected sound make, equal angles with the normal and all three are in the same plane., , Echo: In bigger monuments and in large empty halls you can hear reflections of your, sound after you speak something. This effect is known as echo. The sensation of sound, persists in our brain for 0.1 seconds, so to hear echo the time difference between, original sound and reflected sound should be more than that., As you know speed of sound in air is = 344 m/s And 344 x 0.1 = 34.4 metre, So, the minimum distance required ‘om a reflecting wall or surface, should be half of 34.4, means it shd S., , 3 of 4, , Reverberation: Repeated reflection: S in persistence of sound and is, called reverberation., , Use of Reverberation of Sound: Following instruments use this property of sound:, , a © <