# Search results

2. ### Basic terminology in Non Linear Analysis

I am new to non linear dynamics, I am reading some papers and there are terms that I am finding every which I still have no idea about their meaning. What is: 1. Inhibitory coupling 2. An attractor Any explanation or reference is warmly welcome Thanks
3. ### FITC Fluorescein

Hello, I am a physics student and I am trying to set up a microscale chemical experiment that involves Sulfuric Acid, Feroin, Molonic Acid, Sodium Bromade and water. I want to study the physical behavior of this reaction as I change the concentration of different components such as Sulfuric...
4. ### Potential Invariant under translation

Ok, thanks a lot, now this makes sense
5. ### Potential Invariant under translation

Thank you very much. I calculated [P,V(x)]in x-basis and I found a cosine function. Hence the momentum is not always conserved and hence is conserved at certain values of x.
6. ### Potential Invariant under translation

When I was learning translational symmetry I saw that for translation invariance, i.e [T,H]=0 the momentum P needs to be conserved [P,H]=0. This momentum is actually the generator of small translations defined as T:x→x+ε. Now, I was solving some problems and I met one which is...
7. ### Circular Harmonics

I have a problem consisting in solving for potential in 2 dim polar coordinates where I am asked to use circular harmonics. Can I still use Legendre polynomials (since these are actually for spherical harmonics)? If not what are their analoguous in polar coordinates?
8. ### Center of mass of a system of two photons

How can one calculate the center of mass of a system made of two photons? I know that they have zero rest mass so the first intuition is to say that they do not have any center of mass. However, I read about something called center of momentum which is defined as a frame in which a moving...

10. ### Converting noise into electrical energy

Do you have any reference (paper, book, ...), please?
11. ### Winning a lottery

Yes that's what I mean
12. ### Winning a lottery

Hi everyone, There is a lottery where in every 100 tickets 10 of them must win. Now, me and my friends want to try. We are 6 and we wish to play such that at least 3 of us win. Can anyone help me and tell me what is the probability that this happen? Thank you.
13. ### Mixed state vs. pure state

Thanks for your explanation. But now, let's take a physical example: "LIGHT". I've been reading that Light Polarization would help in the understanding of pure and mixed state. Suppose I have a beam of light which can be polarized or not. As I read, a polarized light (photon) is a pure state...
14. ### Mixed state vs. pure state

Can you please suggest me any reading which gives more details. And thanks
15. ### Mixed state vs. pure state

In quantum mechanics, regarding light (photon), how to tell that a wavefunction is in a pure state or mixed state? I am learning these stuffs for my first time. I have attempted to answer that question but I am not sure: a wavefunction can be wrtitten as a linear combination of linear...
16. ### Physics Careers in physics?

I agree that not everything but frankly, almost anything. I was just referring to engineering. Of course a physicist can work in medicine. Find out what radiologists do or what is medical physics. Long time performance and innovation for his firm. Compare the percentage of unemployed lawyers...
17. ### Who/what is behind earthquakes?

Hello everyone, After observing these last consecutive earthquakes in history, i asked myself: is it possible to induce an earthquake? I do not know if this is the first time that our planet goes through a such period of successive strong earthquakes. If yes, do you still thinking that...
18. ### Physics Careers in physics?

The most beneficial choice for anyone is to do what he likes (or he loves). This was the case for me, my parents wanted me to do biology but i could convince them. Now am doing my PhD in softmatter physics and I find it awesome.
19. ### Physics Careers in physics?

Although not directly, Physics can do everything, that's right. The main skill that physicists have is that they understand many things faster than anyone else. I bet that if you are a BSc in physics and you want to get into robotics, six months of training in robotics are good enough and you're...

21. ### Resources for Physics Lab Sessions

Dear all, In this coming fall, I will be assigned Physics Lab as a teaching assistantship. Does anyone know a book or any other resource that can help me in mastering physics lab challenges. I need a book on measurements and instrumentation where i can find data manipulation techniques. Does...
22. ### Career of someone with PhD in microfluidics

Hello everybody, What kind of job (career) that someone with PhD in Physics (Microfluidics) can handle? I am interested in that field and i would like to know what kind of jobs i can do after i finish my PhD (Apart from post-doc). Thank you
23. ### Converting noise into electrical energy

I also think that increasing the yield should violate thermodynamics laws. And about about the point that a turning fork is able to break a glass may be depending on the structure of the glass and the resonance phenomenon. May be kwaekins should have some interesting ideas to share but he has to...
24. ### Converting noise into electrical energy

Look, am sorry I could not carry out this project since at my school, I could not find all the necessary equipment to implement that machine. That I was advised by a teacher that I had chosen to supervise me. However, I still thinking that the key point is the understanding of piezzo-electric...
25. ### Application Fee Waiving for Internationals

Hello! I am a physics graduate student from Africa and I want to apply for post graduate studies in US universities. However, I facing a problem of application fee everywhere except PennState University which request for application fee when you've been admitted. Does anyone know any other...

28. ### Statement of Purpose for us physics grad

ok now i got ur point. My main goal is to become a professor in physics of matter such that i can introduce a physics PhD granting program in my country. About myself as individual, i have the love of physics and i have collaborated I am many different research projects
29. ### Statement of Purpose for us physics grad

Excuse me, do you mean you're getting nothing from it? is it such fake?
30. ### Statement of Purpose for us physics grad

Dear, here is a statement of purpose that I have prepared for an admission in postgraduate in USA. Please any comment is welcome. ____________________________________________ From many years ago, the discovery and invention of new material has enhanced the world’s development. For...
31. ### Schools Which university with a cheaper Master Programme in Renewable Energy

Hi! I am a finalist student in Applied Physics from an African University and want to pursue with postgrad programs. I have found an organization which supports students from developing countries in Master programs related to Sustainable energy development. There is an opportunity to get...
32. ### Boiling point at a certain pressure!

How can one calculate the boiling of a liquid at a pressure different from standard temperature? Am trying to do it using the ideal gas equation, (PV)/T=(P'V')/T' Where P is the STP, V is 22.4l, T= boiling point at STP, P'= new pressure, V' is the new volume and T' is to be found. But is...
33. ### Superconductivity and electron pair

Hi all! I am learning superconductivity for the first time. As i saw, the supercurrent of some material is governed mainly by electron pair! Now my question raises here, how do those electron pairs form? What are their features compared to single electrons? Here is what i guess: "at very...
34. ### What kind of physists is most sought and more payed

no, they dont
35. ### Compter Engineer Vs Physicist

For sure computer engineers are very sought but once a physicist has gotten a job, he is more payed than a computer engineer. Furthermore, physicists are most respected in society and are open for different careers!
36. ### What kind of physists is most sought and more payed

Hey guys! I am a future graduate student (October 2010) in Applied Physics. I am planning to continue with my Masters Program next year and I have to choose a program by the end of July. My problem is now how does one choose a masters program? To answer this question i tried first to...
37. ### Normal frequencies of vibration of a molecule

Someone told me that there is other approximation (other than rigid-rotator-harmonic oscillator) that can be used to calculate thermodynamic functions of molecules with complex vibrational frequencies. Among them he cited me the "Non-Rigid-Rotator-Harmonic oscillator but i have no clue about...
38. ### Object sliding down smooth quarter circle as a function of time

If you want to use the decomposition methods. I think that the given equations of the system are like constraints of that motion. Then they will help to find the resultant force (or acceleration). If you can decompose the whole motion equate the found equations to those of resultant force, i...
39. ### Magnetic Force of identical shaped box bar magnets

Nice one here! That force is a gravitational one. I hope you realized the inverse square proportionality which means that the force dies as the distance between two magnets poles are far away! Thanks dm164!
40. ### Object sliding down smooth quarter circle as a function of time

Alright, you can use any method to solve that ODE. Remember your initial conditions that at point (-5,5), its speed is 0. Actually if you are allowed to use matlab, it would be very easy! Good luck then!
41. ### Conducting Rod in Electric Field

Yes I think you're right! And remember the concept of bound and free charges.
42. ### Magnetic Force of identical shaped box bar magnets

Wow! Your problem is now getting serious but check this out http://en.wikipedia.org/wiki/Magnetic_field
43. ### Magnetic Force of identical shaped box bar magnets

Use the Biot-Savart law (http://en.wikipedia.org/wiki/Biot_savart) or Ampere's law (http://en.wikipedia.org/wiki/Ampere_law) to express the magnetic field as fuction of distance, you will find that the magnetic field is inversely proportional to distance. To find the magnetic force, you will...
44. ### Conducting Rod in Electric Field

By the definition, the electric potential, as the energy required to bring a point charge from point B to point A, is given by the negative integral of E over the distance dr from B to A. That is, \int^{B}_{A}Edr Just try to apply this on your case where A and B are different positions of the ends.
45. ### Object sliding down smooth quarter circle as a function of time

I worked it on separate paper because i could not write it properly using this Latex codes. Please refer to attached its pdf file . Just let me know if you still have any question. Here is the latex version Here is my attempt: As the mass is slide on a frictionless curve, i can use...
46. ### Object sliding down smooth quarter circle as a function of time

If am getting your point, your task is to find the equation of the motion of a particle on a smooth curve. Just try to use the Lagrangian. But you should first show us how far you have tried! Good luck
47. ### Object sliding down smooth quarter circle as a function of time

If am getting your point, your task is to find the equation of the motion of a particle on a smooth curve. Just try to use the Lagrangian. But you should first show us how far you have tried! Good luck
48. ### Why ideal gases are not used in refrigerator?

thanks Borek. Now it makes more sense.
49. ### Why ideal gases are not used in refrigerator?

Nice answer Borek! I appreciate it. But what if we assume noble gases such He and Neon or even natural air to be ideal (as we do always), can these be used in refrigerators?
50. ### Why ideal gases are not used in refrigerator?

I read somewhere that a special fluid, called hydrofluorocarbon, is used in refrigerator. It carries hot temperature from the refrigerator and put it out. They says that it has a low specific heat capacity and low liquid/gas transition point (room temperature). Now my question is why ideal gas...