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Can someone please help me by solving/explaining j09 / 21 / q5
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help needed physics as 9702
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Asalam-o-Alaikum!
Question 5.
a. 1) The amplitudes of the sound waves from the two sources S1 and S2 must be the same so that the crest of one can cancel out the trough of the other.
2) The path difference between the waves from S1 and S2 must be (n + ½)λ.
b. for this question here's what you need to do: draw a line from S2 to M and find the length of that line by using
Pythagoras' Theorem. a^2= b^2 + c^2 --> (100)^2 + (80)^2 = 16400, square root 16400 gives you 128 cm. So now path difference is 128 - 100 = 28 cm.
They tell you that the speed of sound is 330 m s–1 so using formula c=fλ we find out using values 1.0 kHz to 4.0 kHz to see between which two wavelengths the minima lie.
330/1000 = 0.33 m = 33 cm
330/4000= 0.0825 m = 8.25 cm
now using formula (n + ½)λ, 28 = (n + ½)λ...n can be any number 1, 2, 3 and so on.
when n is:
1, wavelength is 18.667 for getting minima
2, wavelength is 11.2
3, wavelength is 8
4, wavelength is 6.222
you already see that we don't need to go any further since we have got the wavelengths that lie between 33 cm and 8.25 cm, which are 18.7 and 11.2. And that's your answer.
Question 5.
a. 1) The amplitudes of the sound waves from the two sources S1 and S2 must be the same so that the crest of one can cancel out the trough of the other.
2) The path difference between the waves from S1 and S2 must be (n + ½)λ.
b. for this question here's what you need to do: draw a line from S2 to M and find the length of that line by using
Pythagoras' Theorem. a^2= b^2 + c^2 --> (100)^2 + (80)^2 = 16400, square root 16400 gives you 128 cm. So now path difference is 128 - 100 = 28 cm.
They tell you that the speed of sound is 330 m s–1 so using formula c=fλ we find out using values 1.0 kHz to 4.0 kHz to see between which two wavelengths the minima lie.
330/1000 = 0.33 m = 33 cm
330/4000= 0.0825 m = 8.25 cm
now using formula (n + ½)λ, 28 = (n + ½)λ...n can be any number 1, 2, 3 and so on.
when n is:
1, wavelength is 18.667 for getting minima
2, wavelength is 11.2
3, wavelength is 8
4, wavelength is 6.222
you already see that we don't need to go any further since we have got the wavelengths that lie between 33 cm and 8.25 cm, which are 18.7 and 11.2. And that's your answer.