MCS-PHYSICS-9E

Home work:                   Chapter SOUND                       18th April,2020                

Dear Students,

I hope you have completed the first homework. I am giving you notes which have to be done in continuation to the previous homework.

Characteristics of Sound wave.

1. Compressions and Rarefactions : 

Compressions are the regions where medium particles are crowded together and the density as well as pressure are high. On the other hand Rarefactions are the regions where medium particles are spread apart and the density as well as pressure are low.

2. Amplitude :

• The magnitude of maximum disturbance (pressure or density) in the medium on either side of the mean value is called amplitude of sound wave.
• Amplitude is usually represented by the symbol A. 
• The SI unit of Amplitude of sound is Metre(m).

3. Wavelength :

• The Distance between two consecutive compressions or two consecutive Rarefactions is called Wavelength.
• It is usually represented by the Greek letter (lambda) λ.
• the SI unit of Wavelength is Metre(m).

4. Frequency :

• The number of oscillations completed per unit time by the Sound is called its Frequency.
• It is represented by a Greek letter (Nu) v, it can also be represented by f.
• The SI unit is hertz(Hz)

5. Time period:

• Time taken between two consecutive compressions or rarefactions crossing a point is called time period of the Wave.
• It is represented by T. 
• The SI unit of time period is seconds(s).

6. Relation between frequency and time period of a wave

• If T  be time period of a wave then as per definition of time period,                  No. of oscillations completed in time T = 1.                                                    No. of oscillations completed in unit time = 1/T.                                              But the number of oscillations completed by a wave per unit time = frequency of a wave,                                                                                          Thus,               f = 1/T  

7. Wave speed

• The wave speed is defined as the distance which a point on the wave, such as a compression or a rarefaction, travels per unit time. 
• It is represented by v.
• The SI unit of the wave speed is m/s.