Question

Three coherent sonic sources emitting sound of single wavelength lamda are placed on the x axis at points

Answer 1

Answer:

question_answer Two coherent sources S1 and S2 are separated by a distance four times the wavelength l of the source. The sources lie along y axis whereas a detector moves along + x axis. Leaving the origin and far off points the number of points where maxima are observed is

A)            2    

B)            3

C)            4    

D)            5

 

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Correct Answer: B

Solution :

          From ΔS1S2D, (S1D)2=(S1S2)2+(S2D)2 (S1P+PD)2=(S1S2)2+(S2D)2  Here S1P is the path difference =nλ for maximum intensity. ∴(nλ+xn)2=(4λ)2+(xn)2 or xn=16λ2−n2λ22nλ Then x1=16λ2−λ22λ=7.5λ x2=16λ2−4λ24λ=3λ x3=16λ2−9λ26λ=76λ x4=0. ∴Number of points for maxima becomes

Explanation: