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Topic Question Set

Q 1 :    

In a guitar, two strings A and B made of same material are slightly out of tune and produce beats of frequency 6 Hz. When tension in B is slightly decreased, the beat frequency increases to 7 Hz. If the frequency of A is 530 Hz, the original frequency of B will be          [2020]

  • 523 Hz

     

  • 524 Hz

     

  • 536 Hz

     

  • 537 Hz

     

(2)

Frequency of string A, υA=530 Hz and beat frequency Δυ1=6 Hz.

Since, υB=υA±Δυ1, we have υB=536 Hz or 524 Hz

Now, when tension on the string is reduced, its frequency reduces.

Now, the beat frequency, Δu2=7Hz

∴   The original frequency of B, υB=524Hz

Q 2 :    

Three sound waves of equal amplitudes have frequencies (n-1),n,(n+1). They superimpose to give beats. The number of beats produced per second will be   [2016]
 

  • 1

     

  • 4

     

  • 3

     

  • 2

     

(4)