All Questions

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Frequency and Wavelength peak for Wien's displaement law of a blackbody [duplicate]

This is a question relating to Wien's displacement law for the Planck function. As we all know frequency and wavelength are related to the speed of light by: $$\nu\lambda=c$$ However, why is it ...
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how do photons move with respect to EM (I'd like to picture wave magnitudes frame by frame)

(I'm aware treating photon as particle and talking about its position is not exactly, conceptually right but I think it makes sense, at least in the point of view of a beginner. Please just assume ...
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Obtaining an equation regarding isothermal compressibility

The isothermal compressibility $\kappa_t$ of a substance is defined as $$\kappa_t = -\frac{1}{V} \left ( \frac{\partial V}{\partial P} \right )_T$$ Obtain an expression for the isothermal ...
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Is it possible for a planetary system to orbit around something that wasn't a sun?

Say for example that at the center of our solar system you replaced the sun, with something that wasn't a star, lets say that it was electrified and still produced the same amount of heat, would that ...
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What really is mass?

I was always taught that mass was how much matter something is made of, but I recently read that it is how resistant an object is to acceleration; as such, you could add mass to an object by ...
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Reverse spinning wind generator [on hold]

I broke a blade on my wind generator. The maker says they have new blades that rotate the opposite direction now. At first that sounds like a no-go, but then after thinking about it, the wires are ...
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Is the superposition of stationary states a stationary state? If not, then why not?

I am a beginner in Quantum mechanics and as I understand,the superposition of stationary states is also a solution of time-independent Schrödinger equation (TISE). The wave functions that are the ...
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I am trying to draw the Feynman diagram for the following scattering amplitude (f a fermion) $$i\mathcal{M}(f\overline{f}\phi\phi\phi)$$ Given the following interaction term in the Lagrangian: $$... 1answer 42 views What happens if locally manifold is seen as an Euclidean space? [on hold] I have been trying to understand the definition of a manifold and I have found out that the most common definition can be paraphrased as: A manifold is a space that has a complicated "topology" ... 1answer 20 views 5UDH Tandem electrostatic accelerator What does UDH stands for in the name of an electrostatic accelerator 5UDH-2 Tandem accelerator? Does it is related to its working or just a trade mark? 0answers 22 views Higher-dimensional Manifolds examples? [on hold] We know in Einstein's general theory of Relativity, the space-time is taken to be 4-dimensional manifold. My question is what are other theories that can take higher than four dimensional manifolds. ... 0answers 14 views Homogenous Linear Equations in the form of Determinants [migrated] In Arfken's "Mathematical Methods for Physicists" How did he arrive to: x_1/x_3 = \frac{(a_2b_3-a_3b_2)}{(a_1b_2-a_2b_1)} Starting from:-$$ a_1x_1+a_2x_2+a_3x_3=0 ; \\ b_1x_1+b_2x_2+b_3x_3=0 ; ...
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I am starting to learn Quantum mechanics. I can't wait for my completion of QM, as I am running behind all the concepts taught in the class; but I can't even go on studying chemistry, or I can't even ...
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Finding $U(S,V,N)$ for ideal gas, given $pV=NkT$ and $U(T)=N c_V T$

Given the experimental results for the ideal gas, I want to recover the internal energy expressed in its natural variables as: U(S,V,N) = \alpha e^{\frac{S}{N c_V}} V^{\frac{c_V-c_p}{c_V}} ...
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Diffraction of light

If $l_1$ and $l_2$ are parallel how can they both can hit same spot? Why their difference in path length is $l_2 - l_1 = d \sin \theta$ instead of 0?
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What equations are needed to describe how two bodies interact?

For a small project I am thinking about making a 2D game in which there are two planets, each of a random size, and when you run the game it will show how those planets interact due to gravity. I'm ...
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Electric field inside a sphere [on hold]

Problem: A sphere with radius $R$ has a spherically symmetric charge density that varies radially as $1/r$. What is the electric field outside and inside the sphere? Equations: $E=kQ/r^2$, ...
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Why is the charge of a proton positive? [duplicate]

Is there a reason that a proton has a positive charge while an electron has a negative charge? Are these just names that were given to the charges or was there a reason for making a proton have a ...
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Mimicking Free Fall

I was thinking about this situation with a friend of mine, and we had opposing views: Suppose you have a frictionless table with mass M resting on top. You attach a chain to the mass M, a chain with ...
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What determines the rate of vibration decay of a metal?

Suppose we have a tuning fork in a vacuum and strike it. Is there anything in the theory of metals that would predict that the tuning fork's vibration amplitude would decrease with time. Put another ...
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Change of energy levels in statistical mechanics with heat

Why is it, that energy levels dont change if a system is heated at constant volume? "When a system is heated, the energy levels are unchanged but their populations are changed" If i add heat to a ...
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How high can the temperaure of a body be raised using a heat pump [on hold]

I have a homework problem for my stat mech class. In the problem there are 3 bodies where the initial temperatures are $300\,\mathrm{K}$, $300\,\mathrm{K}$, and $100\,\mathrm{K}$. Here we are ...
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Power and frequency of photons and its relationship with biological safety

I understand that x-rays are more dangerous than radio waves because they are of higher energy, since they have higher frequency. However, it’s less dangerous to stand near a radio station with a ...
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Problem in understanding Feynman's explanation of the Dirac-Delta function

This is quoted from Feynman's Lectures' Normalization of the states in $x$: We return now to the discussion of the modifications of our basic equations which are required when we are dealing with ...
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Primitive unit cell of fcc

When I consider the primitive unit cell of a fcc lattice (red in the image below) the lattice points are only partially part of the primitive unit cell. All in all the primitive unit cell contains ...
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How do I calculate the speeds in x, y, and theta of a spinning rod?

Suppose the object looks like the diagram below (it is the horizontal rod). On the vertices, are two velocity vectors $v_r$ and $v_l$. The question is: how is the motion of the rod affected by these ...
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Relative displacement of a point in a deformed object

I have a model and it undergoes translation and rotation at different time steps.I want to know the displacement relative to some point in the model which is kept as my reference.How will I determine ...
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Engineering Physics - Gravitational and Kinetic Potential Energy [on hold]

For part 1, I need to 'substitute all unknown numbers into the equation for potential energy' and leave X as a variable. In the picture below I've included the question and details that I've been able ...
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Why water reflects light? [duplicate]

Please explain clearly: Why water reflects light? Why do we see our image on calm water? What is the Maxwell equation? What is Fresnel reflection? Please answer my questions. My exam is ...