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36 views

Number of bosonic states in a $n$ particle system

Lets assume we have a system of three particles in which three energy-levels labeled by $$E_1, E_2, E_3$$ are occupied. We want to write down all states that are symmetric (bosonic). One symmetric ...
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0answers
26 views

The velocity of sound in terms of Fermi velocity

Assume this question: In a simple model of a monovalent metal consisting of point positive ion cores embedded in a uniform jellium of electrons, a value for the average energy for electron is: $$E = ...
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1answer
63 views

What can cause a change in wave's shape - One dimensional wave

what can cause a change in wave's shape of one dimensional wave moving through a rope? It's velocity ? or the wave's length ? What can cause him change his shape.
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1answer
68 views

Spring Constant - Waves

I tried to prove that for the same length of spring , a one dimensional wave that moves faster in spring 2 than spring 1, its spring constant will be lower than the spring constant of spring 1. ...
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3answers
66 views

How can I compute the angular velocity of a triangle formed by three particles knowing their instantaneous positions and velocities? [closed]

I have a set of trajectories of three particles and their instantaneous velocities. I would like to compute the 3 components of the angular velocity pseudovector of the fictive triangle formed by ...
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0answers
83 views

Hydrogen Transition Rate from n',l to n',l'

I am trying to solve Problem 9.22 in Griffiths' Intro to Quantum Mechanics (2nd Ed.) that asks to show the spontaneous emission rate for a transition from n,l to n',l' in hydrogen is given by ...
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1answer
50 views

What is the difference between a linear and non-linear solution in the bending of beams?

I have been working on a simulator for bending of beams and came now to a tricky doubt: What should be the difference between a linear and non linear solution in this case (graphic at bottom)? The ...
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20 views

Flux, intensity, etc in ferromagnetic core by integral

Cheng, Field and Wave Electromagnetics (newest ed.), ex 6-10, page 252 Some of the examples in this book are kind of sloppily described. Having trouble with this one. We have a toroidal core with ...
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1answer
195 views

Calculating the expectation value of a Hamiltonian

I want to calculate the expectation value of a Hamiltonian. I have a wave function that is $$\psi = \frac{1}{\sqrt{5}}(1\phi_1 + 2\phi_2).$$ I want to know if I set this up properly. The ...
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0answers
251 views

Visualizing Tension in FBD — Rope With Mass

Asked to find the tension of a point that is halfway up a rope (where the rope has mass), given the system: The solution of the problem (FBD included) is as follows. In this diagram (Tm = tension ...
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0answers
92 views

Truss Analysis with multiple moments creates linear combinations

So in my engineering statics course we have been doing a great deal of work with trusses and machines, and a part of the physics behind it has really been confusing me. Just as a note, I also have ...
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1answer
58 views

First Order Time Depenent Perturbation theory of particle in magnetic field

So I am dealing with the following hamiltonian, and the following perturbation: $$H=-\mu B_0\sigma_z$$ $$V=\mu B_1(\cos(\omega t)\hat x-\sin(\omega t)\hat y)\cdot{\bf \sigma}$$ I am asked for the ...
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0answers
23 views

Breakdown voltage

Capacitor (Geiger counter) is made out of wire with radius $R_1 = 5 mm$ and coaxial tube with radius $R_2 = 5 cm$. What is the maximum voltage on the capacitor, given the breakdown voltage of air ...
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1answer
106 views

Fraunhofer Diffraction using lenses [duplicate]

I've come across a question that I don't know how to tackle: An alternative way of observing Fraunhofer diffraction uses lenses to provide appropriate conditions. Sketch an optical configuration ...
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1answer
295 views

What is the difference between virtual object and virtual image? [duplicate]

What is the difference between virtual object and virtual image?
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2answers
87 views

combination of cells

There are m*n identical cells of emf E and internal resistance r connected in parallel rows. This combination of cells is connected across an external resistance R. For what arrangement of the ...
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0answers
46 views

Ground state of spin in magnetic field

I am trying to solve a time dependent perturbation theory problem, and it involves the Hamiltonian $$H=-\mu B\sigma_z$$ And a perturbation $$V=-\mu B_1\sigma\cdot(\cos(\omega t)\hat x-\sin(\omega ...
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2answers
202 views

Relative motion. Setting course of closest approach (Requested resource recommendation as well)

Let $r_{P/Q}$ be the position vector of $\overrightarrow P$ relative to vector $\overrightarrow Q$ and $v_{P/Q}$ the velocity vector of $\overrightarrow P$ relative to $\overrightarrow Q$. Suppose ...
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1answer
108 views

Finding the odd parity bound state wave function for a particle in one dimension

Let a particle of mass $m$ and energy $E$ be moving on the $x$-axis in a potential $V(x)$ given by $$V(x)=\left\{\begin{matrix} -V_{0}, & -a<x<a\\ 0, & otherwise \end{matrix}\right.$$ ...
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1answer
84 views

Temperature in a Voltaic Cell

The potential difference across a voltaic cell varies with temperature. But my question is whether the voltage increases or decreases as temperature rises. According to the Nernst equation, the two ...
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1answer
98 views

Normalizing the sum of wavefunctions and calculating probabilty - understanding concepts

A state of a particle bounded by infinite potential walls at x=0 and x=L is described by a wave function $\psi = a\phi_1 + b\phi_2 $ where $\phi_i$ are the stationary states. So let's say we want to ...
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0answers
64 views

Force between two charges containing several dielectrics between them

The following question is quite similar to mine. Dielectric modification of electrostatic equations? However, the answer does not prove satisfactory to me. The formula given in the above problem ...
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0answers
45 views

Question on dielectric sphere

The question is: Suppose the field inside a large piece of dielectric is $E(0)$ so that $D(0) =$$\epsilon(0)E(0)$ + $P$. Now a small spherical cavity is hollowed out of the material. Find the ...
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1answer
46 views

Coordinate System vs. Angular Properties vs. Centroid

Please help me check my understanding related to the rotational motion of a 3D rigid body after reading some Physics textbooks and googling for some more materials (e.g., Wikipedia's Torque, ...
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0answers
51 views

Deduce magnetic field based on electric field

I'm learning Maxwell's electromagnetic equations and i can't wrap my head around this problem: Given the volume $x\in [0,1], y\in [0,1], z\in [0,1]$, electric field $\vec E(x,y,z,t)$ and material ...
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2answers
94 views

How is $\text{PE} = qV$ derived using knowledge of $F = \frac{q_1q_2}{4\pi \epsilon_0 r^2}$

I recently started grade 11, and this concept confuses me, since if we place a charge $q$ on a potential $V$, I do not completely comprehend what values would need to be substituted which would give ...
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0answers
31 views

Self-inductance of a toroidal inductor

I am trying to determine the self-inductance of a toroidal coil of mean radius $R$ with $N$ loops of radius $a$ with a current $I$ flowing within them. I have calculated the magnetic field by noting ...
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0answers
19 views

Do I ever not account for temperature variation from wall temperature in pipe flow?

Let's say I have internal pipe flow with a constant wall temperature. If I evaluate the properties at either the mean inlet temperature of the average of the inlet and outlet, do I always have to ...
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1answer
41 views

A pearl that moves in a smooth vertical hoop (Circular motion) [closed]

I couldn't understand something about the situation of a pearl that moves in a smooth vertical hoop in circular motion. When the normal force equals 0 , the pearl didn't disconnect from the smooth ...
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1answer
51 views

Calculating electric potential from a changing electric field

Assuming that I calculated the electric field in a single point between a uniform charged positive sphere and an infinite long wire charged positive uniformly. Now, I want to calculate the velocity of ...
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0answers
48 views

Trace of Spin Products Using Rotation operators

So I am working on this problem involving the trace of spin matrices. I am trying to solve for $Tr(S_iS_j S_kS_l)$ using rotation operators. I know how to go about solving for $Tr(S_iS_jS_k)$. It is ...
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1answer
59 views

Calculating a radioactive sample's mass from its activity [closed]

The question reads as such: "What is the mass of a 1.05 µCi carbon-14 source?" First I convert to decays/s: $R = 1.05 µCi=3.885 \times 10^4 decays/s$. The half-life for carbon-14 that we've been ...
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1answer
54 views

Ohms Law Voltage/Potential Difference [duplicate]

Three 2.0 Ω resistors are connected in series to a 12 V battery. What is the potential difference across each resistor? � This question requires Ohms law because V is needed right? So I would use I = ...
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0answers
26 views

Question regarding 2 conducting spheres connected by a long fine line (electric potentional)

I'm having a bit of trouble understanding a pretty simple issue. Assuming I have 2 conducting spheres uniformly charged connected by a long fine line (as shows in the added photo) and im being asked ...
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0answers
35 views

Magnetic forces and generators

i'm really struggling to break this question down into manageable chunks and identify which quantities are relevant. I'm also unsure of some of the wording in the question. A bar of length ...
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2answers
87 views

Collision of two balls of finite radius [duplicate]

This is your typical elastic collision problem except the balls have finite radius. To be clear: two billiard balls in the plane each with radius $\sigma$ move at constant velocities $v_1, v_2$ ...
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2answers
52 views

Energy realized in fusion and electrons?

I was doing this question about the energy released in a fusion reaction: In the mark scheme it included the mass of the electrons (for part cii) on the left and just used the mass of protons for ...
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0answers
25 views

Sum of independent errors [duplicate]

During a physics lab we stumbled upon a little problem. The measuring device was unstable, oscillating between two values. We were told to write down the average with the half-difference between the ...
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0answers
41 views

Angles between axes after Lorentz transformations

Consider frame $K_1, K_2, K_3$ such that $K_1$ moves along the $y$ axis of $K_2$ with speed $v$ and $K_2$ moves along the $x$ axis of $K_3$ with speed $u$. Find the angle between the $x$ axis of $K_1$ ...
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2answers
64 views

How to deal with non fixed springs? [closed]

In every physics book they explain how to compute the force that a spring exert if one of its ends is fixed to a wall (or equivalent) and the other end is compressed or stretched. But how to deal ...
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3answers
93 views

Weird resistor patterns [closed]

I came up with the following question: The vertices of tetrahedron ABCD are all connected by 1-ohm resistors. What is the total resistance between A and B? I haven't the faintest idea how to ...
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0answers
32 views

Question regarding temperature as a property of a system

This is probably silly question but I got stuck while reading “Lectures on Theoretical Physics-Thermodynamics and Statistical Mechanics” by Sommerfeld. In the first chapter it says : Temperature ...
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0answers
46 views

What is a non-linear capacitor?

I'm new here. I have a (maybe dumb) question: What are non-linear capacitors? I'm given a circuit including a capacitor and the question says The given capacitor is non-linear with the ...
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3answers
71 views

What is the purpose of the factor $N/L$ in the magnetic field of a solenoid?

I am supposed to find the expression of the magnetic field on the axis of a solenoid of radius $a$, length $L$, and with $N$ the number of turns. So in order to find $dB$ (to integrate over dx), I ...
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0answers
52 views

Classical rod-wall-floor system

I have a homogeneous thin rod $AB$. $A$ can slide along $z$-axis, $B$ along $xy$ plane. There is no friction. We have any initial conditions. Now the question is to write down the equation of motion ...
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0answers
51 views

Thermodynamics First Law Question - Expansions

Two thermally iso- lated cylinders, A and B, of equal volume, both equipped with pistons, are connected by a valve. Initially A has its piston fully withdrawn and contains a monatomic gas at ...
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0answers
52 views

Charge Amplifier response and frequency response [closed]

I am getting ready for my final and have completed everything on my study guide except for two questions I cannot figure out. Here is the first question: I have gone through all my lectures and ...
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1answer
66 views

Friction influencing the motion of a mass and non-inertial frame of reference [closed]

So... recently a Newtonian-mechanics related exercise has raised in me many questions basically ragarding which forces influence a given system and how, I know they might sound bit too "noobish" but I ...
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1answer
37 views

Taking signal travel time into account in Special Relativity

I am having problems taking the time it takes for a light signal from an event to reach an observer into account: For instance, if we have two observers $A$ and $B$ who synchronize their clocks when ...
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0answers
59 views

How to find density matrix?

The Beam-splitter matrix is $ B = \frac{1}{\sqrt{2}}\begin{pmatrix} 1 & 1\\ 1 & -1 \end{pmatrix} $. I want to apply $a^{\dagger}_{1}a^{\dagger}_{2} |00\rangle_{12}$ as the input state for ...