An observer `A` is moving directly towards a stationary sound source while another observer `B` is moving away from the source with the same velocity. Which of the following statements are correct?A. Average of freqeuncies recorded by `A` and `B` is equal to natural frequency of the sourceB. Wavelength of wave received by `A` is less than that of waves received by `B`.C. Wavelength of waves received by two observers will be same.D. Both the observers will observe the wave travelling with same speed.

An observer `A` is moving directly towards a stationary sound source w

1.	An observer `A` is moving directly towards a stationary sound source while another observer `B` is moving away from the source with the same velocity. Which of the following statements are correct?A. Average of freqeuncies recorded by `A` and `B` is equal to natural frequency of the sourceB. Wavelength of wave received by `A` is less than that of waves received by `B`.C. Wavelength of waves received by two observers will be same.D. Both the observers will observe the wave travelling with same speed.
Answer» Correct Answer - A::C Let velocity of each observer be `u` as shown in the figure. `_Ararr^u` `_Brarr^u` Then freqeuency received by `A` will be `n_1=n_0((v+u)/(v))` where `n_0` is natural frequency of the source and `v` is sound propagation velocity. The frequency received by `B` will be `n_2=n_0((v-u)/(v))` Since `((n_1+n_2))/(2)=n_0`, therefore, option (a) is correct.

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