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So, in this problem I just solved there is a force field given by $\mathbf{F} = -x \hat{\mathbf{j}}$ and I need to compute the work done on a particle along a circular path of radius $R$, centred at the origin, clockwise direction. I checked that the correct answer is $W = \pi R^2$.
So, what I'm confused about is that ... |
I don’t understand the answer to part b. Why the disk won’t rotate about its center of mass if it is mounted to the rod by a frictionless bearing. Why can the disk be a mass point at the end of the pendulum?
Please don’t close the question, I’m not asking the answer. I want to know the difference between fixed and fr... |
What prerequisite knowledge do I need for starting QM?
I know basic calculus of class 12th standard (pre college). I am aware of methods of substitutions, standard integrals, definite integrals, integration by part and have a good idea about functions. I also know quite a bit of matrices an linear algebra, vectors , 3d... |
For a free Dirac fermion of mass $m$ in four dimensions coupled to an external gauge potential $A^\mu(x)$, classical equations of motion for the fermion lead to the equation for the divergence of the axial current $j^\mu_5=\bar{\psi}\gamma^\mu\gamma^5\psi$:
\begin{equation}
\partial_\mu j^\mu_5+2im\bar{\psi}\gamma^5\ps... |
My textbook and wiki/online articles all claim that work is given by the integral
$$W=\int_\gamma\vec{F}\boldsymbol{\cdot}\text{d}\vec{s}$$
where the $\text{d}\vec{s}$ is some infinitesimal step along the path gamma, and force is a function of position. This means, as a function of position, the force at every point in... |
We find first of all that it requires us to assume that gravitational propagation is not instantaneous, but occurs with the speed of light. One might think that this is reason enough to reject the hypothesis, since Laplace demonstrated that this cannot be the case.3 In reality, however, the effect of this propagation ... |
In my opinion, the wire must expand due to the magnetic force acting radially outwards on two diametrically opposite ends of the loop as a result of the equation:
F = I(dl × B)
Where B is the magnetic field due to the loop which is perpendicular to the plane of the loop.
|
In the shown speed - time graph for a body thrown vertically up there is a sharp kink in the graph at the instant for which body is at highest position ie not differentiable so we can't find acceleration. But at this highest point acceleration is due to rate of change of speed only as no angular velocity is there at h... |
One thing I have not fully understood is what field strength renormalization is. In Peskin & Schroeder's book "An Introduction to Quantum Field Theory" (Section 7.1) they introduce it as as a term $Z$ that makes all the math work out and do not elaborate further. But what exactly are we renormalizing and how is this ca... |
Years ago it was asked here how to calculate the tidal heating of a moon orbiting another body with a simple equation. The answer is very detailed. They explain the equation, its shortcomings, the approximations made, the constants and variables used, etc.
The entire equation is proportional to a variable: −Im$(k_2)$. ... |
I'm learning AP Thermodynamics and the textbook I'm learning from states that the properties of an ideal gas are independent of the type of gas but the kinetic theory of gases states that the temperature of the gas and the average translational kinetic energy of a molecule are related by the formula:
$$
\frac{1}{2}m\la... |
Picture source: Lesics at t=189 and t=205.
I recently visited a friend who just had MRI scan. From his explanation, I have some question about magnetic power applied to him.
Consider a B magnetic field strength is applied to him when he was being had MRI diagnose, which the B is sum of the main magnetic field strengt... |
One electron volt is defined as the kinetic energy of a electron in a potential of $1$ volt.
Hence, by conservation of energy, electric potential energy = kinetic energy:
$$ q V = \mathrm{K.E.} $$
As the charge of an electron is $-e$ and the voltage is $1\mathrm{V}$, the kinetic energy would be $-e$ joules, which will ... |
I want to know in which situation the disk rotates about its center of mass? It seems it’s in the first situation when it’s fixed. But how does it rotates if it’s fixed and what does cause it to rotate?
And if so, how to determine its moment of inertia for pivot $P$? Can I use parallel axis theory when the disk rotate... |
Why do you need a wave function $\psi$ for quantum mechanics? Can't you just make a differential equation involving just the p.d.f. $|\psi|^2$ of a particle? Since basically with quantum mechanics the point is, given $\psi(x,0)$, to find $\psi(x,t)$ with the help of the Schrödinger equation
$$i\hbar\frac{\partial}{\par... |
I want to find a closed expression of the focal length of a graded index since I don't manage to find any on the internet. I already checked this out: Determining the focal length of a gradient index lens
But they didn't seem to finalize the result and the technique of their derivation is unfamiliar to me.
The lens has... |
I want to know if photon density changes over time. By density, I mean number of photon hitting a surface in time. I am not asking about the direction of emission which is random. What I mean is that for example if on first second for example 10 photons hit the sensor, the other second in time will the number be same o... |
I would like to know how much the real orbit of satellite can differ to the elliptic one.
Some perturbation of mass center position of the satellite must occur - Earth gravity accelaration changes as it is not a perfect ball. We can also take into account influence of varying gravitational force from secondary bodies -... |
I'm a bit familiar with the concept of gravitational lensing. I also believe that all objects have some gravitational force, even if it's minuscule.
Would an object as massive as a person cause any gravitational lensing? Even an extremely miniscule amount from any position?
Bonus points if you somehow quantify the magn... |
When we solve the Schrodinger equation for the Helium atom, we usually resort to approximation methods citing that it cannot be exactly solved analytically.
When it is said that it "cannot" be solved does that translate to "an analytical solution does not exist" or "nobody has yet found a way to solve it exactly analyt... |
It is well known that the wave equation agrees with special relativity. So, my question is: it is possible to derive the Lorentz transforms from the equation?
First, I started by assuming a linear transformation of the form:
$$
t'= \alpha x + \beta t \\ \; \\
x' = \gamma x + \delta t
$$
The wave equation in the S frame... |
Usually, we call instanton a "pseudoparticle", but does it have spin? I know the similar soliton--skymion does have a spin 1/2 (which actually depends on color number $N_{c}$).
I used a general argument, which is rotating instanton and seeing the change over phase, and reckoned that action's change is $\sim\frac{8\pi^{... |
$X$ is a closed manifold with a positive-definite metric $g$.
$M_2$ is a 2D oriented closed manifold with a positive-definite metric $G$ and a compatible volume form $\omega$.
We can then consider the following Euclidean path integral for a $X$-valued scalar field $\phi$ on spacetime $M_2$:
$$\int\mathcal{D}\phi\,\math... |
Say we have a law of physics in a form of a differential equation:
$$
F(x,y,\dot{y},\dots) = 0.
$$
What is the general algorithm to show that this law is invariant under a certain transformation. The problem I am solving is electromagnetism laws under Galilean transf. but I want to learn the general mathematical approa... |
This should be a pretty quick answer but I can't figure it out.
I read somewhere that in an atom ionization energy and potential energy have the same absolute values, but it doesn't really make sense to me, how could they be equal if potential energy gets bigger as u move away from the atom while ionization energy gets... |
I was watching this Ted Ed video on Youtube about the twin paradox and found the explanation with the spacetime graph a bit confusing. At 3:00 in the video, they show a graph and explain how bursts are sent by each twin to measure how much time has passed for the other twin.
My understanding is that at least during the... |
It is actually not a question. I am giving a chain of arguments here , I believe at some point I made a mistake. I want the mistake to be pointed out.
/1. The probability of an event in an ideal experiment is given by the square of the absolute value of a complex number Φ which is called the probability amplitude:
P = ... |
Just saw a video about how the shadow on moon is pitch black.
That took me to the question of scattering. I have myself asked a question similar to this already.
When light from a bulb(consisting of whole blackbody spectrum) hits/interacts with the air molecules, it gets absorbed. Then, the molecules and electrons of m... |
Two stars, S1 and S2, orbit each other around a common center of mass, the barycenter.
M1 and M2 are their respective masses.
R1 and R2 are their respective distances from the barycenter.
D is the distance between their two orbital centers.
I found the following in wikipedia: https://en.wikipedia.org/wiki/Binary_star
R... |
For a non-ideal transformer, is the following equation still true?
$$
\frac{V_S}{V_P} = \frac{N_S}{N_P}
$$
All the books I have consulted (mainly first-year undergraduate physics textbooks) merely proved the above equation using Faraday's law of electromagnetic induction for the case where the transformer is ideal. Yes... |
I'm trying to compute the time evolution operator of a system with the following hamiltonian:
$$ H(t) = g(t)[\sigma^+ e^{i \omega t } + \sigma^-e^{-i \omega t }] $$
I tried to use the Magnus expansion, and computed
$$[H(t'), H(t'')].$$
Not like a similar hamiltonian, but with the operators $a$ and $a^\dagger$, this com... |
We all know that we hear sound due to vibration in air. So I was wondering if we make an oscillator which does not make any internal sound, but it oscillates at more than 20Hz will we able to hear any sound due to those vibrations in the air (assuming amplitude is loud enough that we can hear)?
|
I am starting to work with tensor network and I wanted to know how to get the eigenvectors of a Matrix Product Operator (MPO).
As far as I know when one is trying to diagonalize his Hamiltonian he needs to specify the indices how to truncate the Hamiltonian, and my question is how to choose the right and left indices?
... |
Screw gauges usually have a least count of 0.001cm. The digital meters measure it more accurately, using laser having a frequency of about 500Hz to 30kHz. However, it doesn't work for substances such as glass, which have greater wave-absorbing properties than that of [most] other substances. Is there any device -digita... |
I am learning about special relativity, and I just read about how it helps us to solve some "puzzles" that arise in questions involving charged particles. The first "puzzle" was about how a charged particle travelling parallel to a neutral wire behaves, and I understand this completely. What I do not understand is anot... |
Free-fall kinematics gives 1.43 sec until the diver hits the water. $\omega$ is easily found from 2.5 rev/1.43 sec = 1.75 rev/s = 11 rad/sec. My question results from the following: Kinematics also gives -14 m/s = v just before the diver hits the water. Equating this value (the magnitude) for the linear velocity of ... |
I am having trouble understanding how to calculate the energy dispersion relation $E(\vec{k})$ in a given direction within the first Brillouin zone.I can find the vectors in the reciprocal lattice. Any pointers?
Thank you
|
I have started reading in particle physics very recently. I have been reading a bit about tau particles, and I came across the idea of CP symmetry and how it’s violation may present an explanation for matter-antimatter asymmetry in the universe.
I read a simple explanation for CP symmetry stating that, for example, an ... |
Causes of Experimental uncertainty can range from limited accuracy of the equipment to variation of environmental conditions. Is there a way to address these experimental uncertainty through model of computation uncertainity? In other words is there any common cause of computational uncertainty and experimental uncerta... |
I'm studying electromagnetism and I came upon an apparant contradiction in the calculation of the magnetic field above the center of a current loop.
The setup is given in the image, I want to calculate the magnetic field in a point above the center of the loop, at height $z$. When this is done with Biot-Savart, you get... |
Suppose we have three frames of reference, A and B, and a lab frame. Taking the lab proper time as the coordinate time, we can draw worldlines for A and B. B is stationary in the lab frame, so its worldline is a straight line at $x = x_B$. A initially moves at a constant speed $u$ until time $t=t_A$, at which point it ... |
Some context:
In the literature, there is different ways of using the word "state". A quick overview on this:
Some say a "state" is a mathematical object, to be precise either
a) a ray (set) of (normalized elements) of the usual hilbert space $\mathcal{H}$ (e.g. Marinescu (978-0-12-383874-2) on p.24) - again there s... |
We know that through GR, in a gravitational field light bends twice as much as predicted by strict Newtonian physics. In researching this I've found explanations like light bends on both the space and time components of spacetime on page 116. And in the PBS Spacetime at 10:50, he says that it is caused by the wave fr... |
Say we have a square metal plate $A$, 1 $m^2$ on each side, of negligible thickness, in a vacuum with no other objects nearby and no other heat coming into the system. Say its temperature is at an equilibrium of 20°C.
Using the Stefan Boltzmann Law we calculate that $A$ will be radiating 418.8 W/$m^2$ or 837.6 W total ... |
I am reading Szabo - 1967 - Modern Quantum Chemistry. In Chapter 3 P122, it mentions that the spin orbitals $\left|\chi_a\right\rangle$ obtained by the Fock operator
$f\left|\chi_a\right\rangle=\varepsilon_a\left|\chi_a\right\rangle$ can have the symmetry of the molecule. (form a basis for an irreducible representation... |
I'm trying to explain what causes an image to be distorted when seen through a water droplet.
Specifically, my example is that of a drop of water on a car window. We can see that the image is reversed, which I understand as I take the droplet to act like a planar-convex lens. However, the image is also heavily distorte... |
Some context:
Usually, one describes states formally through elements of a Hilbert space $\mathcal{H}$ (e.g. the n-dimensional vector space of complex numbers with the standard basis and standard scalar product). This way the representation is not unique - two representations $|\psi_1\rangle$ and $|\psi_2\rangle=e^{i\g... |
I want to know what happens to an electron when fired in a projectile motion. I tried to apply the Heisenberg's Uncertainty Principle, but I had no idea. Does it's range, and maximum height reached, and total time of flight differ?
|
If two blocks are resting on top of each other and are on the ground, the weight of the upper block causes an equal and opposite reaction force on the lower one (Newt 3rd) and the same happens for the lower one on the ground
There must be friction between the two blocks but I don't understand how to caluclate it using... |
Okay, this is most likely incorrect since I only have a prerequisite of algebra-based physics and did not take any calculus-based physics yet. I have however taken Calculus 1 and 2 and am quite proficient. I was wondering if there was a formula I could derive to find the average torque of a rod given the radius of the ... |
Once you roll a biased dice $x$ number of times, it becomes clear wheter or not it is biased. This is because one number will come up more times than the usual chance i.e. 1/6. You can improve your results by increasing the number of trials.
But is there a way to determine the bias without having to roll the dice? Can ... |
If I understood correctly from Griffiths' explanation of the ladder operators as applied to the quantum harmonic oscillator, the ladder operators represent increasing/decreasing the energy level of the wavefunction and this happens by increasing/decreasing the eigenvalues. I've also seen it said in some other physics ... |
I am confused about the use of the formulas for the spinor outer products $$\sum_{s=1}^2 u_s(p)\bar u_s(p) = \gamma^\mu p_\mu + m $$
and
$$ \sum_{s=1}^2 v_s(p)\bar v_s(p)= \gamma^\mu p_\mu - m,$$
where $u_s(p)$ and $v_s(p)$ are a basis of spinor solutions to the Dirac equation $(i\gamma^\mu p_\mu - m)\psi = 0$, i.e.
$$... |
People say that the image forms behind the mirror in the case of plane mirrors. But I feel that they must take place on the mirror. I cannot come into terms with this explanation.
|
There already exists posts to discuss this question, but I don't think it's totally done!
We can write the covariant derivative as
$$D_i=\partial_i-igA_i^aT^a \tag{1}$$
There are two kinds of opinions about the integration by parts (IBP) of $D_i$
First opinion, $D_i$ is constructed to satisfy the Leibniz rule, see this... |
Is there a way to design a double-slit experiment such that, if you put a detector in one place it indicates collapse, and in another case it indicates superposition, and you can extract information about which path was taken?
For instance, if the particles are acting like waves, then any part of the region directly be... |
I'm studying human physiology. And there is a often repeated notion that blood flows "from areas of high pressure to lower pressure". I was wondering why that is so. However there is no real explanation for it. I understand that in a gradient the force points into the direction of low pressure. Further research on the ... |
I know the ladder operator for harmonic oscillator can be obtained by factorization method, can the same method be applied to oscillators with potential $V(x)=x^{4}$ (the Duffing case) or higher degree like $V(x) = x^{2l}$ ? Or is there any result about their ladder operators?
Further Notes: We can surely get the integ... |
I am wondering how the "buckling number" of a timber column is altered by having a vertical element attached to it. Blue line is a roof, green a concrete wall and black is the timber column and the beam.
I am basically asking what happens to "K" as described here:
https://en.wikipedia.org/wiki/Buckling#Columns
or how t... |
The relations $\vec{D}=\epsilon \vec{E}$, and $\vec{P} = \chi \epsilon_0 \vec{E}$ imply that all three fields have the same direction. Is this always true in the case of static source charges and some dielectric material surrounding the charges?
|
Perhaps counter-intuitively, radiative heat transfer equations show that if you have an internally-heated plate with constant energy input (eg electric resistance heating with constant power, or a constant light source) in a vacuum, it will reach a certain equilibrium temperature $T$, and if you then bring a cold plate... |
I've caught by a loop of:
Standard texts of Non-Relativistic Quantum Mechanics $\to$ Representation theory of Lie groups and Lie algebras of $SO(3)$ and $SU(2)$ $\to$ Discussions of infinitesimal transformations and formulas like $\Lambda_{\alpha}^{\beta} = \mathrm{exp}\Big(\frac{1}{2}\Omega_{\mu\nu}(M^{\mu\nu})_{\alp... |
The cat righting reflex (Wikipedia article) allows a cat to change its orientation in the absence of initial angular momentum or external forces. A theoretical model would work like this: the cat bends its spine $90^{\circ}$, then performs the maneuver in the animation below (also from Wikipedia) ...
... then straigh... |
I have some trouble understanding what is the physical meaning of the vacuum expectation value (VEV) when applied in a QFT context.
Question: What is the physical meaning of a VEV?
I understand that it is the expectation value of some operator on a specific state, so the question can also be casted in the form:
What do... |
How do telescopes see many billion light years distant object in our universe?
As an individual with limited expertise in the field of astronomy, my current understanding suggests that the observation of the furthest points in the universe using telescopes requires an unobstructed line of sight. However, with billions ... |
Problem 6.8 on p. 39 in David Morin's The Lagrangian Method gives a stick pivoted at the origin and rotating around the pivot with constant angular velocity $\dot{\alpha}$ (which is given as $\omega$ in the document). A small mass $m$ can slide frictionless along the stick. The problems asks to find the conserved energ... |
In my coaching institute my teacher said that charge can neither be created nor be destroyed, But when ionise an atom and give it some charge (+ or -), there we are creating charge and my teacher also said that charge cannot be converted into energy but we do convert charge to mechanical energy in DC motor. Can you ple... |
Citing from Spin-orbital Yu-Shiba-Rusinov states in single Kondo molecular magnet, the introduction starts by saying that the exchange coupling between magnetic impurities and Bogoliubov quasiparticles of a superconductor leads to low-energy bound states inside the superconducting gap known as Yu-Shiba-Rusinov (YSR) st... |
Yesterday, while on a treadmill I saw a power reading of 250 watts next to a calories /hour of ~1000. The established conversion rate of 1 watt = .860 kcal/hour would imply an hourly rate of 215 kcal, so what explains this disparity? Does this have to do with some inefficiency of the human body in converting calories f... |
I am trying to figure out an easy way to identify the generator of the following matrix group:
$$ \begin{bmatrix}
e^{x} & 0 & a \\
0 & e^{-x} & a' \\
0 & 0 & 1
\end{bmatrix} $$
In this case this is the Poincare group but I was wondering what is a "non-formal" way to find a basis and hence the structure constants of a... |
I was studying the topic -"Fixed Axis Rotation " from the book Kleppner Kolenkow -The Introduction to Mechanics. Please clarify the meaning of the $v_j$ variable which I have indicated in the photo below. If I interpret $v_j$ as the speed of particle j, even for $\vec v_j$ restricted to the $xy$ plane that seems wrong... |
In an undergraduate thermodynamics book, the authors use the case of free expansion of an ideal gas to argue that the internal energy $U$ of the gas depends only on its temperature $T$. I'm not sure if the authors mean to say that $\biggl(\frac{\partial U}{\partial P}\biggr)_V = \biggl(\frac{\partial U}{\partial V}\big... |
Imagine you have a pair of 2-dimensional circular portals, with one placed perfectly above the other (practically the same as portals in the Portal games). A spherical object is held between the portals and then dropped, enabling it to fall endlessly. The room this occurs in is a perfect vacuum and the sphere has 0 sid... |
In this kind of situation, is it theoretically possible for a ball to stop at the top of the track?
Because when I try to apply the circular motion formula it tells me that, since at the top there is gravity, $mg=\frac{mv^2}{r}$ even when velocity is least.
However when I apply energy $\frac{1}{2}mv^2=mg(2R)$, the bal... |
I have now come across two different definitions for the spinodal curve which, together with the coexistence line, encloses two metastable phase regions. The first definition is from Tong on page 139. In considering the van der Waal's liquid, one throws away the unphysical phase, which has negative compressibility. How... |
Well, the Morris and Thorne article on wormholes states that the function $\Phi(r)$ of metric
$$
ds^2 = -e^{2\Phi(r)}c^2dt^2 + dr^2/(1 - b(r)/r)+r^2(d\theta^2 + sin^2\theta\hspace{0.1cm} d\phi^2)
$$
must be finite for all values of $r \geq r_0$ to avoid singularities, but I did not understand why this avoids singu... |
Suppose I am performing calibration of a pinhole camera under the Brown–Conrady distortion model and find the focal length $(f_x, f_y)$, principal point $(c_x, c_y)$, radial distortion coefficients $K_i$, and tangential distortion coefficients $P_i$.
I repeat the calibration process in air and in fresh water, in identi... |
This question has been asked several times already but it usually involves pushing against the Earth or a rocket carrying the fuel within itself. Let's simplify the problem to a projectile pushed by a light beam from an external power source.
So a projectile is pushed by a light beam from Earth to achieve velocity $v$... |
The problem states that a ball is dropped from rest and falls under the influence of gravity (neglecting air resistance). At the same time, another ball is thrown with an initial velocity of v0 from a point that is 10 meters horizontally away and 5 meters below the first ball (see figure in the problem statement). The ... |
If two quantum particles are entangled they can no longer be fully described individually. The two of them together have only one wave equation.
Doesn't this mean that we are actually dealing with a single Siamese twin sort of thing?
I don't understand how, after entanglement, they can still be described as two separat... |
Is it possible to change frame of references 2 times? Being more specific, if I have a Hamiltonian $$H = H_0 + H_a + H_b,$$
i can go in the interaction picture and have my new interaction picture hamiltonians
$$H_a^i + H_b^i$$
The time evolution operator now would be
$$U(t) = U_0(t) U^i(t)$$
Where $U_0(t)$ is the time ... |
I'm reading something that talks about the ideal construction of an atom(Aufbau), and it says '' For the ideal construction of an atom, imagine an atom of nucleus of charge +1, inside its electric field add an electron, forming like this the atom of atomic number 1''
Notice that this was translated and it might not be ... |
This question is about understanding the term "free electrons" in conductors.
Online one can find that free electrons concentration for copper is around $8.5\cdot10^{28}
\space m^{-3}$. If we have a copper rod of length $L=1\space m$ and cross section area $A=10^{-4} \space m^2$ then the charge from free electrons is ... |
So I have two questions that are related to each other. In an AC circuit, a resistor is connected to an AC source. My book says that the applied voltage has to overcome the potential drop in the resistance only. What does the word “overcome” mean here? Similarly in AC through an inductor, the book says there is not pot... |
In some texts (see [1],[2],[3]) the two particle interaction operator is defined as:
$$
V_{int.} =\frac 1 2\int d\mathbf{r}d\mathbf{r'} V(\mathbf{r},\mathbf{r')} \psi^\dagger(\mathbf{r})\psi^\dagger(\mathbf{r'}) \psi(\mathbf{r})\psi(\mathbf{r'}).
$$
Whereas other texts (see [3], [4]) explicitly order the terms (suggest... |
A lot of textbook or lecture note that teach linear response theory would calculate AC conductivity first and then say that the DC conductivity can be obtained from taking the limit of frequency to zero. I don't understand how this can be possibly true.
The AC connectivity might be calculatable from linear response wit... |
In introduction to elementary particles by David Griffiths p.227, Griffiths says that
$$(\beta^kp_k + mc)(\gamma^{\lambda}p_{\lambda} -mc) = \beta^k\gamma^{\lambda}p_kp_{\lambda} - mc(\beta^k - \gamma^k)p_k - m^2c^2$$ while deriving the Dirac equation.
However, I don't understand how he gets the second term on the righ... |
The question is written in section $2)$
1) Introduction
1.1) QCD
For a non-abelian group, the connection term on the lagrangian will be written as
$$\mathcal{A}_{\mu}=A_{\mu}^{a}T_{a}\tag{1}$$
This notation is far from be explicit and this brings me all sorts of confusion. I came from a classical pseudo-Riemannian back... |
Summary
I am taking an intro. to quantum mechanics course and was taught that superposition exists until we measure the system which makes the wave function of a quantum system collapse. I have a basic understanding of superposition, probabilities etc. However, what I couldn't manage to understand is how we are sure if... |
Does the Hagen–Poiseuille equation apply within the entrance length region of Incompressible, Newtonian fluid flow in a perfect tube?
|
Suppose a positive point charge is moving in a plane and there is a uniform magnetic field directed into the plane. My textbook (Young and Freedman) claims that because the Lorentz force exerted on the point charge is always perpendicular to its motion, it follows a circular path (or helical in the general case). The t... |
[This paragraph has been added to make clear that this is not a homework question having been branded as such by a mod of some kind. The question is attempting to the core of a very important question relating to causality in Quantum Field Theories. The whole point of QFTs (or at least one of the main points) is that t... |
Recently started doing some reading into fictitious forces. It's easy enough to understand when dealing with linearly accelerating frames but I find it more challenging to understand rotating frames like the earth or a merry-go-round. Can someone clarify if I make any errors in the following statements?
If I was sittin... |
Let's say an astronaut with a terminal illness that gives them one year to live on Earth travels to a star one lightyear away, travelling at almost the speed of light. Suppose they perceive that the trip takes them 55 days or so, due to time dilation. Will they still be alive when they reach their destination? What wil... |
Here's what I have understood so far.
(Im talking about electric spark we see in a gas lighter,as shown in the picture)
When high voltage is generated at the central metal piece, electrons fly off the metal due to high electric field produced. These electrons strike the air molecules and make them loose their electron... |
Using $dV/dr = -E$ it is mathematically possible to prove that there exists a point in space where gravitational potential is zero but field is not.
But what is the physical feasibility of the above situation.
Also given the fact that negative mass is not possible, is there a point in the real universe satisfying the g... |
Consider a container filled with ideal gas and is covered by a frictionless and lightweight piston that exerts pressure on the gas.
I understand that during an isobaric process, the container is in contact with a pressure reservoir, ensuring that the gas is in mechanical equilibrium with its surroundings for the whole ... |
I wanna work with this climate model, the idealized greenhouse model. The Wikipedia page explains it very well with an example using one layer of atmosphere. Then it mentions that you can add more layers to model more powerful greenhouse effects. And there are some examples online with two and three layers. But what ar... |
I am a bit confused about this idea. When ONLY a voltmeter is connected to a cell, there is no current flow since the voltmeter has infinite resistance. So, the voltmeter gives the reading of the actual emf since there is no voltage across the cell's internal resistance (as I=0).But if there is no current flow at all, ... |
I'm studying electromagnetism at the moment, more specifically Griffiths and I stumbled upon something I don't understand.
So, the solutions to Maxwell's equations in free space ($\rho = 0$, $\mathbf{J}=0$) are electromagnetic waves, represented by the standard wave function: $Ae^{i(kx- \omega t)}$.
Now, suppose a char... |
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