Term Definition and 742 Threads

The http://en.wikipedia.org/wiki/Fine_structure#Darwin_term" contains a (3D-)delta function as a result of taking the Laplacian of the Coulomb potential. I'm trying to find out why. I've been searching, and I've so far come across different views of the Laplacian of 1/r at the origin. Either...

I'd just like to make sure that I understand this question: "The nth tern of a sequence is n2 - 2. Find the value of the 20th term of the sequence." Is the question asking me to find the value of the equation if n = 20? (In which case the answer would be 20 x 20 - 2 = 398)

We were taught in the vibrations and waves lecture course that the solution to the wave equation for traveling waves is of the form ψ(z,t) = Acos(wt-kz). In the Electromagnestism course we learned that EM waves are traveling waves and have the solution E = E0cos(kz-wt). I know that changing...

I am doing my final year B Tech in electrical engineering, but my interest is in theoretical physics. Though I have applied to some US universities for applied physics with the hope that I can switch to theoretical physics later but am not sure if I will get admission. Can anyone suggest me...

Write a recursive rule for each of the following sequences: (a) 41, 42.5, 44, 45.5, 47, 48.5, 50, … (b) 300, 30, 3, 0.3, 0.03, 0.003, … (c) 2, 6, 8, 14, 22, 36, … ----------------- a) Tn+1 = Tn + 1.5 b) Tn+1 = 0.1Tn c) ? For C, The difference is 4, 2, 6, 8, 14, I've figured out...

Homework Statement There are three charges arranged on the z-axis. Charge +Q_2 at the origin, -Q_1 at (0,0,a) and -Q_1 at (0,0,-a). Using spherical polar coordinates (i.e the angle \vartheta is between r and the positive z-axis), find the potential at a point with a distance r from the...

Hey, I am wondering how to solve this heat equation with a 'generation' term included. In one instance I am adding the generation term, in the other I am subtracting it. a\frac{\partial^{2}f }{\partial x^{2}}-\frac{\partial f}{\partial t} - \lambda f = 0 a\frac{\partial^{2}f...

I am in the Mechanical engineering co-op program. For those unfamiliar with this program, instead of taking 4 years to finish my degree I have taken 5 years and have earned 1 year of work experience. I will have my final work term in the summer and I've been debating which job I should take...

Hello! Trying to measure the magnetic field of the Earth here. Basically, measured the deflection of the current carrying wire in the vertical plane. However, the sag of the wire due to heat overwhelmed the displacement due to the magnetic field. If I plot displacement of wire against current, I...

help plis... Hello I study physics in chile. I am doing my thesis in "brane world and gauss bonnet term"...i studied randall sundrum 1 and 2 models, and some paper abaut the topic...My teacher of thesis does not help me... I need find a topic abaut this subject that has not been done...My...

Term Symbol for Carbon Total Angular Momentum 1. Write the term symnbols for carbon atom He2s22p2 which has two equivalent p electrons taking into account the Pauli exclusion principle. 2... 3. Since the carbon has two equivalent p-electrons, we know the l1=1 and that l2=1 as well. Also the...

Homework Statement y''-49y=7cos(7x)+7+e^(7x) The Attempt at a Solution I have no idea how to solve this Differential equation. I could solve one that has y''-49y=one term, but I'm stumped with more than one. First, I get the homogeneous equation, y''-49y=0 and fine y_c, then use the...

Homework Statement Find the term in the expansion of (x-(2/x^2))^14 which is of the form constant/x. The Attempt at a Solution I have worked out the general expression. (14|r) x^14-r * (-2/x^2)^r However I can only work out this problem by trial and error. I know that in this case...

In chemistry, we are always hearing the term 'stability'.But i am really confused , or can't get the actual meaning of that term.When i asked my friends, they said that stability can only be explained in a given situation.for example, A ball at a height above the Earth's surface is not...

Hi everyone, I'm studying electron-electron scattering, starting with the Dirac equation it ends up calculating the invariant transition amplitude, defined as: -iM=(ie{\overline{u}^f}_A}\gamma^\mu u^i}_A) \frac{-ig_{\mu\nu}}{q^2}(ie{\overline{u}^f}_B}\gamma^\nu u^i}_B) With u_A and u_B the...

If George W. Bush were serving a third term as president now, what state do you believe our country would be in?

In books I find that the Majorana mass term for the neutrinos is given by m_L \nu_L^T C^\dagger \nu where C is Dirac Conjugation operator. How does C look like if I write \nu_L as in terms of its two components \left(\begin{array} (\nu_{L1} \\ \nu_{L2} \end{array} \right)? Is C=...

ODE Series Solution Near Regular Singular Point, x^2*y term? (fixed post body) Homework Statement Find the series solution (x > 0) corresponding to the larger root of the indicial equation. 5x^{2}y'' + 4xy' + 10x^{2}y = 0 Homework Equations Solution form: y =...

term "frame-jumping" I've come across internet discussions where the term "frame-jumping" is used. As far as I can tell from googling, it seems to come up a lot in discussions involving anti-relativity kooks. I looked in the indexes of some relativity books I own, and couldn't find it. Googling...

Hi... Would you please advise me what does gauge fixing term do (physical point of view) ? Does it eliminate unnecessary spin components from lagrangian for example: Vector particle has two (massless case) or three (massive case) degrees of freedom. Vector itself has four, and a vector...

Homework Statement Homework Equations The Attempt at a Solution Ive numbered the solution steps, the ones that are giving me trouble are from 1 to 2 and from 3 to 4 From 1 to 2 i don't understand how there can be an exp(x) term taken out of the bracket and still be in the...

I'm currently studying the Taylor series and I cannot figure out how the remainder term came to be. If anyone could clarify this for me, I would be really grateful ...! I understand that the Taylor series isn't always equal to f(x) for each x, so we put Rn at the end as the remainder term...

The Hamiltonian for particle in an EM field is H = 1/2m (p - qA)^2 + q phi If we take the cross-terms, which corresponds to the paramagnetic term, we have H para = -q/2m * (p.A + A.p ) = iqh/2m * (\nabla .A + A.\nabla) What I do not understand is how this simplifies...

Hi, Just out of idle curiosity - why do we talk of "time dilation" in terms of special relativity when in fact it contracts which is the opposite? Is there a reason or is it just accepted usage?

I was just doing a simple 2-body Newtonian gravitation problem. The force on each mass is: f=\frac{G m_1 m_2}{r^2} and the integral of the force wrt r is: \int \! f \, dr = -\frac{G m_1 m_2}{r} So, since there are two forces in the system, one on each object, I had assumed that there would...

i am now reading a prl paper the authors used numerical simulations to study a nonlinear system in some parameters, the authors state that system enters into chaos My numerical simulations are the same as that of the authors in the regular regime but in the chaos regime, my...

Why the term "cylindrical functions" for the states in LQG? I just can't find a any reference that explain the why of the term "cylindrical" for the states in LQG. Thanks in advance for any comment. Z.

i am now reading a prl paper the authors used numerical simulations to study a nonlinear system in some parameters, the authors state that system enters into chaos My numerical simulations are the same as that of the authors but in the chaos regime, my simulations are quite different...

Does anyone actually use the term "ensemble interpretation"? People have been asking questions about the "ensemble interpretation" here lately. It's mentioned on the Wikipedia page "interpretations of quantum mechanics" and has its own page. But is that term actually used in books and articles...

Term Paper: "Is the brain immunologically privileged?" I have to write a term paper for my neuroscience class and the theme is "Is the brain immunologically privileged?". According to my professor I have a pretty nice introduction that explains the anatomical aspects of the brain that makes it...

What is meant by the term "gauge singlet"? Can anybody please explain what is meant by the term "gauge singlet"? To be more specific, I got the term in a discussion on wess-zumino lagrangian where the superpotential contains the term:a_i \phi_i . The author claims that in order the theory to...

The IPCC and the term "most" An online "sparring partner" brought up an interesting point during one of our regular (some would say never-ending) climate debates the other day. He asked me for clarity on what the IPCC means by "most" in their Fourth Assessment Report when they say: "Most of...

Homework Statement If you make the change of variables: x= ucos(\theta)-vsin(\theta) y= usin(\theta)+vcos(\theta) where the angle 0 \leq \theta <\pi/2 is chosen in order to eliminate the cross product term in: 4x2+8xy+6y2=30 What is the angle you would use? Homework Equations...

Hi, I am just trying to understand Special Relativity by reading http://en.wikipedia.org/wiki/Introduction_to_special_relativity All is ok except where in "The Minkowski formulation: introduction of spacetime", the introduction of -(ct)^2 term is not clearly justified (or so it seems to...

I was thinking about this earlier today: The last 10 years or so has seen a steady increase in undergraduate research activity and the prevalence of undergraduates contributing to published research articles. I think inevitably this will lead to publications being required, at least informally...

This is a random question and I'm not scientifically oriented (which is obviously why I'm posting here). If the origin of 'fossil' fuels as we know them came from the leftovers of biological species, why is 'fossil' fuel not called 'tree' fuel? Sure it sounds stupid, but there have been...

Hello all, I'm sure you all know the standard relation between torque and angular acceleration: \tau = I\alpha However, in reading a doc on kinematics this weekend, the author gave the following formula for torque: \tau = I\alpha + \omega \times L My question is, from whence...

How can I expand this term ∇∙(φuu) and ∇∙(T×u) ∇∙(φuu) where φ is a scalar and u is a vector and ∇∙(T×u) where T is a second order tensor and u is a vector.

Why is the divergence operation called the 'divergence?' What is the significance of this operation on a vector-valued function? And what about "the curl?" The curl seems self-explanatory (at least it does in electrodynamics), but I need someone to expound on 'the curl' as well.

I have been asked to solve a diffusion equation with a source term using finite differences method. I need to numerically integrate the following equation either in MATLAB or C++. The equation is dT/dt = d2T/dx2 + S(x) The form of S(x) is some function given by a Gaussian profile...

What does the term "complementary interval" mean? I'm studying the Cantor set and related notions right now, and I keep coming across the term "complementary interval." What does that mean? I can't find a definition spelled out anywhere!

I know how to go about solving differential equations of the form y''+q(x)y'+t(x)y = 0 through the methods of finding the characteristic polynomial of the differential equation and solving for the roots, etc. But what I am not clear on is how I would go about solving an equation like this where...

Hi guys, I'm looking to find out if there is a ratio between short term and continuous current for power cables. I know that people usually generalize around 5-10 x rated ampacity, but I'm just asking around to see if there is a certain #. On McMaster Carr, the highest rated cable is for...

sum(1/(n(n^2-1)^(1/2)),n=2,infinity) first derivative <0 for x>=2 I(1/(x(x^2-1)^(1/2)),x,2,infinity) x=secT, dx=secTtanT I(secTtanT/(secTtanT),T) ?

I want to make short term investments (currently, stocks I believe). Currently, I don't have any investment knowledge so wanted to know if stocks are better or forex? (edit: learning about them in next few days) I found this website: http://individuals.interactivebrokers.com/en/main.php If...

MTd2 spotted this paper on arxiv and flagged it for us: Yes! I am very glad to get this one. This paper follows up on a March 2009 video seminar talk Giovanni A-C gave at Perimeter. I'll get the link. Yeah, it's easy to google: just say "Amelino Perimeter". This often works, google...

Can this be an equation of a circle x^2+y^2-2hx-2ky+2mxy+r=0

What are some of the methods of finding the general term of a sequence of numbers? for a sequence from n = 1 to n = 6 such as: 1, 3, 6, 10, 15, 21 the general term is: n(n+1)/2. This is relatively easy to find using guess and check, however I was wondering if there was a general...

Firstly, I don't get why the at term on the exponential turned positive (red arrow).. can someone explain that please? And how do I start on this? How do I split it up such that I can do it for t>0 and t=<0? Do I just integrate e^2t between -inf and 0 and integrate e^-t...

=================================== Life is an ability of matter to manipulate itself. =================================== --- So what do you think? PS: originally I thought it up and wrote it here: https://www.physicsforums.com/showthread.php?t=302477&page=2