# All Questions

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### What is the formula of power of a optical instrument?

I have across and have found that power of a lens with surrounding medium of refractive index n is n/f where f is the focal length, the formula n/f=(n'-n)/R1 + (n-n')/R2; But in book it is said that ...
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### How Space Curvature is proportional to Mass in G. Relativity?

In General Relativity, Einstein established that the gravity is due to the curves produced by objects in space. We all know that the gravity is proportional to Mass. The picture Einstein painted ...
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### Is it possible to cut the contents of an atom? (theoretical question)

For example, if I become the size of an atom and were to explore it. Then if I cut the proton, electron or neutron with a knife (remember, this is theoretical), what would happen? Would it blast, or ...
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### Zero vol. at zero Kelvin

Why the volume of a gas become zero at 0 kelvin?Can Bose einstein condensate be considered as a matter? (I mean the vol. becomes zero)
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### Feshbach resonance in simple terms

I was reading up Feshbach resonances in cold atoms and I was unable to grasp the concept. I will tell you what I have understood. We consider two body scattering processes elastic as well as ...
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### Wave Equation - Vibrations & Waves

My question is basically how to do part ii) of this question even with the hint I am confused; the first part was simple; There's no dispersion & vp = vg = sqrt(hg) as required. But how would I ...
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### Optics modelling software

I am looking for software that could allow me to model the internals of my spectrometer. I would imagine some sort of ray tracer that allows me to add mirrors, slits, gratings etc. This way, I can see ...
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### Is it possible to travel ONLY through Time and not Space?

The question is as stated above. I although think, the most probable answer is no, but I really want to know the reason to it. If, One can travel through only space by travelling at the speed of ...
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### Which of the Physics textbooks would you recommend I read this quarter (Analytical Mechanics)? [duplicate]

My Analytical Mechanics class this quarter has one required textbook: "Classical Dynamics of Particles and Systems" by Thornton & Marion and three recommended readings: "Mechanics" by Landau ...
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### Inverse Square Law and extra space dimensions

Newton's famous Inverse Square Law says that in $3$ dimension of space, force is inversely proportional to the square of the distance between a source and a target. I understand that for higher ...
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### How do you derive the Dirac equation for momentum space?

$\require{cancel}$ \begin{align} 0 &= i \gamma^\mu \partial_\mu \psi(x) - m \psi(x) \\ &= \int \frac{d^4 k}{(2\pi)^4}e^{-i k x}\left( \gamma^\mu k_m \tilde{\psi}(k) - m \tilde{\psi}(k) ...
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### Simple question relating to physics prac reports

I am writing a physics practical report relating to the elasticity of materials relating to their momentum in a collision. I have values for the elasticities that are all within 2% of each other but I ...
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### Why do really powerful magnetics have to be really big?

If you want to make a really powerful magnet, that can for example attract golf ball sized metal objects from 15 feet away, the magnetic has to be really big, and really heavy. Why is this so? I don't ...
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### QFT Calculations via Holographic Duality

Holographic duality tells us that there is a duality between anti-deSitter space and lower dimensional conformal field theory. However, what quantum phenomenon, exactly, can we calculate using the ...
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### Gas Pressure in Industrial processes

Can anybody please help with the following? Ammonia is produced by the Haber process where nitrogen and hydrogen combine to form ammonia according to the equation: N2 + 3H2 == 2NH3 If 1 mole of N2 is ...
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### What would a nuclear explosion look like at relativistic speeds where time dilation and length contraction become significant?

Suppose a rocket carrying a nuclear weapon is moving past our planet at very near the speed of light while a stationary observer watches from here on Earth. As the rocket passes directly overhead, an ...
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### Ising model with metropolis algorithm around critical temperature

I'm trying to simulate Ising model using metropolis algorithm. Boundary conditions are periodic. I know how the algorithm works and I have written the code myself. Everything works as it should except ...
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Here's an exercise from Jackson: A plane wave is incident normally on a perfectly absorbing flat screen. From the law of conservation of linear momentum show that the pressure exerted from the ...
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### Ground state for interacting field thoeries

Are there references where the ground state of an interacting quantum field theory is explicitly written in terms of states of the underlying free theory? For example, let us suppose to have a self ...