Qualification > Sciences
ALL CIE PHYSICS DOUBTS HERE !!!
Deadly_king:
--- Quote from: $!$RatJumper$!$ on November 11, 2010, 05:12:06 am ---What is this equation?? I've never heard about it. What is it used to calculate and when should we use it?
By the way, whats phi?
phi/2pi = AB/lambda
Thankx
--- End quote ---
It's the equation of phase difference (phi)
Phase difference = 2(pie) / lambda
Take AB as and phi as phase difference and you'll get the equation :
phi/2(pie) = AB/lambda ;)
$!$RatJumper$!$:
--- Quote from: Deadly_king on November 11, 2010, 05:23:44 am ---It's the equation of phase difference (phi)
Phase difference = 2(pie) / lambda
Take AB as and phi as phase difference and you'll get the equation :
phi/2(pie) = AB/lambda ;)
--- End quote ---
Makes sense. Thank you DK and TJ-56 :)
$!$RatJumper$!$:
--- Quote from: TJ-56 on November 10, 2010, 09:56:29 pm ---5(a)
1. The waves should meet in antiphase at M. ( phase difference = pie)
2. Sources must emit waves having same amplitude.
(b)
So the wavelength ranges from 330/4000 to 330/1000 (v/f) which is 8.25 to 33 cm
The distance from S2 to M is 128 (root(100sqr +80sqr))
So the phase difference is 128-100 which is 28
using the equation
phi/2pi = AB/lambda
as phi must be pi rad, 1/2 = AB/lambda
AB= 28
so making lambda the subject: lambda= (28*2)/n , where n could be 1,3,5,7 (to be out of phase)
so trying out 1,3,5,7 give us 56, 18.7, 11.2, and 8 respectively, as 18.7 and 11.2 are the only 2 values inside the range i calculated at the beginning, then the number is 2
hope that was helpful
--- End quote ---
One other thing i dont get. Where did n suddenly come into this equation from? And how can we take the phase diff to be pie. We dont know if they are completely out of phase. Yes they are out of phase by 28m, but doesnt pie rad mean they are completely out of phase by exactly half a wavelength?
Deadly_king:
--- Quote from: TJ-56 on November 10, 2010, 09:57:48 pm ---Thanx for the answer +rep
But can u explain further part 1 of the question
thanx in advance
--- End quote ---
1. From the equation you can note that mass is conserved.
Total initial mass : 18 and total final mass : 18 -----> ( Add the mass numbers of the different elements and particles taking part in the reaction )
Now you're asked how Energy is conserved.
Energy emitted = delta(m) x c2 = 1.1 MeV
Therefore for total energy to be conserved,
Mass energy of products + energy emitted = Initial mass energy of reactants.
The energy emitted is released in the form of kinetic energy of the alpha-particle. ;)
Hope you understand :)
Deadly_king:
--- Quote from: $!$RatJumper$!$ on November 11, 2010, 05:40:27 am ---One other thing i dont get. Where did n suddenly come into this equation from? And how can we take the phase diff to be pie. We dont know if they are completely out of phase. Yes they are out of phase by 28m, but doesnt pie rad mean they are completely out of phase by exactly half a wavelength?
--- End quote ---
It is said that the microphone M detects maxima and minima of intensity of sound.
Maxima and Minima takes place only when the two waves meet in anti-phase. ;)
The n indicates the number of wavelengths at which the two waves will meet. It may be any number, but in this case since it is in anti-phase it has to be an odd number.
Phase difference = 2(pie) / lambda is used to find the phase difference between two consecutive points only,i.e the two pints are less than one wavelength apart.
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