Answer to Question 3

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Move the microphone to the right by 10 cm. What is the path difference?

Path difference = X Y

X2 = 42 + 1.62 = 16 + 2.56 = 18.56

X = 4.31 m

Y2 = 42 + 1.42 = 16 + 1.96 = 17.96

Y = 4.24 m

The path difference = 4.31 4.24 = 0.07 m

 

Since this is cancellation, the path difference is half a wavelength. 

Therefore the wavelength = 0.14 m

Frequency = speed   wavelength = 340 m s-1 0.14 m = 2400 Hz