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Physics: Post your doubts here!

MiniSacBall

MiniSacBall

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Thought blocker said:
Here you go :) Credits papajohn
Distance S2M =128 (from Pythagoras thereom)
Path difference S2M - S1M
128-100 = 28 (If you do not know this concept then take help from Pacific Physics Vol 2 )

Wavelenght at 1 Khz of sound wave is λ=v/f 330/1^103= 33cm
λ of 4kHz 330/4^103= 8.25 cm

Path difference for minima = odd number of the half the λ
Or simply (2n+1) * λ/2
Put n = 0 in the formula (2*0 +1) λ/2 = 56
Put N= 1 =2(1)+1) * λ/2 =18.7
Put N = 2 2(2) =1) * λ/2 = 11.2
Put N= 4 2(3) +1* λ/2 = 8
Sice λ 56 cm and 8 cm are not within the range of 8.25 to 33 cm, so minima is obtained for λ 11.2 and 18.7cm Therefore two minma are detected.
Click to expand...

Why do we need to calculate path difference i didn't see any use.:p

And did you calculate those, i mean when n = 0 then it will be λ/2 which is 4.125, λ=8.25
I don't know how did you get 56
 
Last edited:
Thought blocker

Thought blocker

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MiniSacBall said:
Why do we need to calculate path difference i didn't see any use.:p

And did you calculate those, i mean when n = 0 then it will be λ/2 which is 4.125, λ=8.25
I don't know how did you get 56
Click to expand...
o_O o_O
It's like this :¬
ODD NUMBER OF HAVE λ = PHASE DIFFERENCE FOR MINIMA

This implies (2n + 1)*λ/2 = 28

(2(o)+1)* λ/2 = (28)---> Phase difference.
Hence λ = 56..
Same with
(2(1)+1)*λ/2 = 28 ; λ = 18.7
and so on..
 
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Browny

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Can anyone please state the number of significant figures wee should leave a answer to in the physics theory paper?:)

Would the CIE examiners cut marks for wrong number of significant figures in the final answers?:)
 
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Browny

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Can anyone please state the number of significant figures wee should leave a answer to in the physics theory paper?:)

Would the CIE examiners cut marks for wrong number of significant figures in the final answers?:)
 
MiniSacBall

MiniSacBall

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Browny said:
Can anyone please state the number of significant figures wee should leave a answer to in the physics theory paper?:)

Would the CIE examiners cut marks for wrong number of significant figures in the final answers?:)
Click to expand...

Well mostly it is 3-2 significant figures, 3 is better as the answer is more accurate and in most of the papers you will find answers in 3 significant figures.
I guess CIE will only cut marks, if the question says 'Write your answer in appropriate number of significant figures', here you should be extremely careful and write in 3 significant figures only, if you don't your marks will be lost.
 
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Browny

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MiniSacBall said:
Well mostly it is 3-2 significant figures, 3 is better as the answer is more accurate and in most of the papers you will find answers in 3 significant figures.
I guess CIE will only cut marks, if the question says 'Write your answer in appropriate number of significant figures', here you should be extremely careful and write in 3 significant figures only, if you don't your marks will be lost.
Click to expand...
But in the mark schemes it varies.
 
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