ALL CIE PHYSICS DOUBTS HERE !!!

[Deadly_king]

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

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$!$]

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 

Makes sense. Thank you DK and TJ-56

[$!$RatJumper$!$]

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

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]

Thanx for the answer +rep
But can u explain further part 1 of the question
thanx in advance

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]

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?

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.

[$!$RatJumper$!$]

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.

ok i get the rad part. But for the n part, isnt it meant to be n+1/2 ? why do you say it should be an odd number?

[Deadly_king]

ok i get the rad part. But for the n part, isnt it meant to be n+1/2 ? why do you say it should be an odd number?

That's right.

When it is (n+1)/2, it usually is an odd number.

[birchy33]

HELP! How do you figure out questions where they ask for the distance between molecules and all that sort of stuff. Like the distance between solid and liquid?

[TJ-56]

1. Form 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

Oh ok.
Thanks alot dk.

[TJ-56]

HELP! How do you figure out questions where they ask for the distance between molecules and all that sort of stuff. Like the distance between solid and liquid?

Well the distance between solid particles and liquid particles are quite similar, but its rather the movement of those particles that differ the most. In gases, the separation of particles are much greater than that of solids and liquids (approximately 10 molecular diameters).
Hope that was helpful and covered your question completely.

[$!$RatJumper$!$]

That's right.

When it is (n+1)/2, it usually is an odd number.

haha no i mean (n+1/2)lambda

[birchy33]

Well the distance between solid particles and liquid particles are quite similar, but its rather the movement of those particles that differ the most. In gases, the separation of particles are much greater than that of solids and liquids (approximately 10 molecular diameters).
Hope that was helpful and covered your question completely.

Hmm I mean in like when you are asked to find the distance between molecules or the RATIO between distance between molecules in a solid compared to  a liquid or gas.

[astarmathsandphysics]

the ratio is cube root(density of solid/density of gas)

[Deadly_king]

Oh ok.
Thanks alot dk.

Anytime buddy

haha no i mean (n+1/2)lambda

Oops.........i mistyped it.

The equation is (2n + 1)/2 or n + 1/2.

This equation is only used when the waves meet in anti-phase, i.e there will be maximum destructive interference.

[$!$RatJumper$!$]

Alright that makes sense now thankx

Ok can you please have a look at S10 P21 Q4b

So, i use y = (D*lambda) / d to find d. Then I did 1 / d to find the answer. I got it right, but then looked at the MS and saw they used d*sin(theta) = n*lambda to find d. Then they did 1 / d to get the answer.

What im confused about is that when are we meant to know what formula to use where?