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Physics: Post your doubts here!

sweetjinnah

sweetjinnah

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U

unique111

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sweetjinnah said:
Question 6ci and ii)
ci) 1. A= decay constant * N
=> (3.76*10^6) = (0.025)*N... solving for N = 4.67*10^15
2. moles= mass/Mr
moles = no. of paticles /Avogadros constant.
Mass= (4.76*10^15) / (6.02*10^23) = ans * 90/1000 solving mass = 6.98*10^-10 kg
Click to expand...
The answer for N is correct, but the equation does not solve it. Could you see this too?
 
papajohn

papajohn

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Musab100 said:
can anyone do this question for me ?
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s09_qp_2.pdf
Q 5
Click to expand...
1a) Path difference (S2M-S1M) b/w the waves from Si amd S2 is an odd number ( 1 3 5...) multiple of half wavelenght
2) Same amplitude at M

The part b is indeed the most difficult question in the history of CIE ;)
B) 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.
Please pray for As for me in CIE if i helped you..
 
princeali97

princeali97

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there is this question which i've seen many times in past papers: describe and explain how diffraction and interference is observed in i) ripple tank ii)microwaves/light.You may use a diagram to explain.
I dont understand what exactly should we include in the diagram.Sum1 pls help me in dis !
 
princeali97

princeali97

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sadiaali said:
Please someone explain me Q6 of part b with the diagram. Please help:cry:
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s04_qp_2.pdf
Click to expand...
Sadia Ali,nothing to worry in this question.Constructive interference occurs when crests of both waves meet.So you just draw a straight line wherever u see the overlapping of the two waves at a point.For destructive interference draw a straight line which exactly is halfway between the first order and the line OX or u can draw a straight line which passes through a crest of one wave and trough of another.Sorry but i can't upload the attachment.I did what i could :/
 
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