Potential Definition and 1000 Threads

[Note from mentor: this was originally posted in a non-homework forum, so it does not use the homework template.] There is a general relation between the work U required to assemble a charge distribution ρ and the potential φ(r) of that distribution: U = 1/2 ∫ ρ...

So I have been wondering: The potential for a point charge at the origin, is described as: (Using the reference point at infinity): V=1/(4πε) * q/r My question is, what happens to this Potential the closer we are to the point charge, and so the closer we would get, the Potential seems to go...

periodic potential how can i show that period is d

Homework Statement True statements about Jupiter as it moves in its elliptical orbit around the Sun include which o the following? I. It has its greatest speed when closest to the Sun. II. It has its greatest potential energy when farthest from the Sun. III. The magnitude of its...

The electric potential can be defined as V = - ∫C E⋅dl where we are taking the line integral along C from some convenient reference point O, where we have set V = 0, to the point r we are trying to find the potential at. Of course, C can be any curve, but it's usually the most convenient to...

Hello! I am going to talk here about a real scalar field for simplicity. If we have a Higgs-like potential for a real scalar field, the graph of the potential looks like a section of a "Mexican hat", with a bump at 0 and two absolute minima at, say, ##\pm a##. This is the plot I see in any book...

Homework Statement My question is more about understanding the task itself, not about calculation. I am supposed to use the poisson equation, to derive the potential inside a semiconductor for a barrier with potential height ##\phi_B## and a donator doping with ##N1 > N2##. Then I should use...

So in my textbook (Introduction to Electrodynamics by Griffiths) it said that inside a conductor, the electric field E would have to zero, since if it wasn't the free charges would move accordingly and create a electric field that cancels the original field. But in a question that soon followed...

Hello, I have this potential: ## V(\chi) = \frac { F ’’ (\chi) [ 2 F(\chi) - \chi F’ (\chi) ]}{ (F’(\chi))^3} ## How to get ## \frac{ d V(\chi)}{d \chi} = \frac{ \chi F’’ + F’ - F’ }{ F’^2} - 2 \frac{ \chi F’ -F }{ F’^3} F’’ ~~~~~~(*)## My trail, ## V( \chi) = 2 F F’’ F’^{-3} - \chi F’’...

Hi, I'm studying MOSCAP at university and there are 3 regions based on Vg. Accumulation Depletion Inversion For P substrate the surface potential increases as I increase the gate voltage (positive). The books say that at Vg = threshold voltage the surface potential is maximum. But why does it...

Homework Statement Which graphy represents the potential energy of the block as a function of time? Homework Equations PE=mgh The Attempt at a Solution First, the potential energy is zero until it reache the top of the incline where the potential energy is maximum. Moving down, the potential...

Hi at all! This is not a homework or simila, so I'm sorry if I post my question in a wrong section, but I do not know where to post it. In the nuclear case, the Wood-Saxon potential is the main empirical potential used to describe the nucleus. What would be the analogue in the atomic case? The...

Hello, I haven't been able to find the answer to this anywhere. When calculating the energy gained by a particle that is accelerated across the gap of two cavities (e.g. Dees in a cyclotron, or charged cylindrical cavities of a linear accelerator), does one need to take into account the size of...

Homework Statement This problem is belonging to a book, which is material for Vietnamese students who will take part in IPhO (International Physics Olympiad). Since this problem is written in Vietnamese, I will try my best to translate it to English: A vacuum diode consists of two parallel...

Homework Statement Show that the variation of gravity with height can be accounted for approximately by the following potential function V = mgz(1+z/re) in which re is the radius of the Earth. find the force given by the above potential function. Homework Equations V = GM/r The Attempt at a...

Homework Statement The z = 0 plane is a grounded conducting surface. A point charge q is at (0,0,a), and charge 4q at (0,-2a,a). Calculate the potential in the region z > 0. Homework Equations V=∑kq/rThe Attempt at a Solution [/B] Use the method of images. V1 = kq/r+ + kq/r- V1=kq(1/sqrt(x^2...

So I'm an Software Engineer, not a physicist, nor a mathematician. So I like to work in the qualitative, not the quantitative. Today I hit on a problem. I've been trying to remove the concept of "down" or "inward" from my thinking of gravity and GR. When people show the concept of space/time...

Homework Statement Homework Equations U=kq1q2/r The Attempt at a Solution W = changeU = Uf-Uo Uf = k(7*(-5) + 7(-4) + (-5)*(-4))/0.1 = -4.3*10^-4 Ui= k((7*(-4))/0.1= -2.8*10^-4 Uf-Ui = -1.5*10^-4k J

The setup for one magnet Introduce a magnet: Inertial Frame 1 (or lab frame) A frame where a magnet is seen to move with uniform velocity v and carries a uniform polarization P while a point charge Q is seen to be stationary at time t=0. Inertial Frame 2 (or material frame) A frame where a...

Homework Statement Homework Equations dV= integral(kdQ/dR) The Attempt at a Solution So, I'm familiar with these type of problems but in 2D (like a line of uniform charge). When the y,z component is added, I'm kinda lost. i know dQ = p*dV= p*dx*dy*dz. (atleast i think it is). also the dR =...

Homework Statement Homework Equations E=KQ/R^2 The Attempt at a Solution I'm kinda confused at what the question is asked. It is in terms of x, but I thought the integral for potential is V=int(Edr)? Also, should it be integration starting from infinity? Why is the integration from -2 to 3...

I have been looking everywhere for a clear explanation for the following: How do I know which way to integrate the electrical field, when I'm looking for the potential between to points? Example: I have to find the potential between the top conducting plate and the bottom conducting plate...

Homework Statement Homework Equations V=kQ/R The Attempt at a Solution The answer is B)kQ/R. It is because V= k(2Q)/R. I don't understand why Q=2Q in this case. Isn't the point on the inside of the outer shell, so the Q for the equation is just Q?

Homework Statement I have attached a problem from within the chapter of my book. I have a question regarding my highlighted part. My question: Is the reason they are saying E= -Q/(ε0A) because they defined the positive "s" axis to the right? and since E is pointing from right to left we say...

Homework Statement A horizontal spring with a constant of 700N/m is compressed 2cm. A ball of mass 200g is placed in front of the spring. The spring is released. The ball slides along a horizontal track for 10cm while experiencing a frictional force of 0.75N. What is the velocity of the ball at...

Homework Statement a)recall that electric potential is a scalar quantity. For a circular ring of radius, R', carrying charge, Q, what is the electric potential at a height,y, above the center of the ring? b)Use your above answer to determine the electric potential at a height,y, above the...

Homework Statement An Electron with an initial speed of 500,000m/s is brought to rest by an electric field a)did the electron move into a region of higher or lower potential? I b) what was the potential difference that stopped the electron? Homework Equations ΔV=ΔU/q ΔU=-W The Attempt at a...

Homework Statement Hello, I am wondering if I am thinking about electric potential correctly: Stop me if I am wrong: V=electric potential, the electric potential is created by source charges altering space around them. If you place a test charge, q, within that space we can say it experiences...

UPDATE: the first 2 assignments are done (i think). I'm stuck on 3. and I have explained in attempted solution what I have tried thus far. I have an important homework assignment due in Electromagnetism, and I have no idea where to start. It has many sub-assignments, but I cannot even figure...

Homework Statement Taking my Electricity and Magnitism course right now and we are in the section in the book of the electric potential. I have some basic questions regarding work and potential energy. Lets say we are holding a ball 10m above the ground and release it. I am defining the ground...

Homework Statement What is the speed of a proton that has been accelerated from rest through a potential difference of -1000V? Homework Equations ΔV=potential difference V=U/q Conservataion of energy U=qEd (d is distance the proton is moving...i think) The Attempt at a Solution Here is my...

Hi, I learned about how PE = U=kq1q2/r is the electrical potential energy for the system. It is found by taking the integral of electrical force and dr from infinity to the point of location we are interested in. So that is the intregral(F*dr) from r=inf to r=ro. My question is that do I...

Homework Statement My textbook is no help, my teacher is no help, so I've found myself here. I am having a difficult time understanding the differences in 1.Electric Potential energy 2. Potential Difference 3. Electric potential Im sure this question has been asked tons of times but I need...

For a particle trapped in a region of length L the de broglie wave for the 1st excited state is a pure sine wave from 0 to 2pi for which the particle momentum can be calculated as 2h/L from de broglie relation Whereas from energy quantisation relation p=nh/2L where n is the state integer,for...

Homework Statement Given an E field, determine if it's a possible electrostatic field. If so, determine a potential Homework Equations ∇⋅E ∇×E The Attempt at a Solution [/B] Just more of a clarification, since my friend and I both attempted this question differently. I took the...

Homework Statement A 0.200 kg object is attached to a horizontal spring with a spring constant of 77.0 N/m. The other end of the spring is attached to a wall in such a way that it rests on a frictionless horizontal surface. A 10.0 N force is exerted on the spring, causing it to compress a)...

I have been doing pendulum problems lately, and I have found 2 different formulations for potential energy of a pendulum. U=mgl(1-cos(Θ)) and U=-mglcos(Θ) The first says U=0 when Θ=0 (at the bottom). The second has U=0 when Θ=π/2 (halfway to the top). Both give the same equation of motion...

Homework Statement [/B] A particle of mass 'm' is initially in a ground state of 1- D Harmonic oscillator potential V(x) = (1/2) kx2 . If the spring constant of the oscillator is suddenly doubled, then the probability of finding the particle in ground state of new potential will be? (A)...

Homework Statement The Lagrangian density for the ##h=h^{00}## term of the Einstein gravity tensor can be simplified to: $$L=-\frac{1}{2}h\Box h + (M_p)^ah^2\Box h - (M_p)^b h T$$ The equations of motion following from this Lagrangian looks roughly like (I didn't calculate this, they are given...

When to use ## V =-\int E ⋅ dl ## or ## V =\int E ⋅ dl ## ? When i use ## V =-\int E ⋅ dl ##. i can not show that P = IV because ##\frac{ln \frac{b}{a}}{ln \frac{a}{b}} ≠ 1## But the solution use ## V =\int E ⋅ dl ## I'm concerned about using "minus" .

Homework Statement If we lift a block with constant velocity, by applying a force mg upwards, is the work done zero?Homework EquationsThe Attempt at a Solution The work done must be zero as the resultant force is zero, what I don't understand is how does the block get potential energy if no...

The potential difference between two points is given ans the negative of integral of E(vector) <dot product> dl(vector) from initial to final points. Therefore, integral integral of E(vector) <dot product> dl(vector) from initial to final point should give the negative of potential difference...

Why is the electric potential of an electron in a capacitor measured from the negative plate and not the positive plate here? This is from Liboff Introductory quantum mechanics 1st(current is 4th) edition: I don't understand why the distance z is measured from the bottom plate if the...

A battery induces an electric field throughout a circuit in such a way that the electric field exists in the wire and the resistance. By moving in the direction of electric field, we expect that the potential decreases no matter we move in the wire or in the resistance. However, we only consider...

Homework Statement Let's consider two wooden logs. We burn the first one at the base of the mountain and the second one on the peak. Which one is releasing more energy? Do they release the same amount of energy? Does the potential energy affect the burning Homework Equations ## \Delta H =##...

Hi! I would like solve this kind of relation: \phi = \int_0^r \phi (r') 4 \pi r'dr' But I don't know how to proceed... Can you advise me ? Thank's in advance !

Homework Statement Consider a point source emitting light of wavelength 5000 A. Light from this source is falling on a metallic cathode of photoelectric cell. It is also given that energy of a photon of wavelength 10,000 A is 1.23 eV. If the source of 5000 A is replaced by 2500 A wavelength but...

Homework Statement in acid medium the standard reduction potential of NO converted to N2O is 1.59V .its standard potential in alkaline meduim at 298k would be? Homework Equations a)2NO+2H ---> N2O +H20 E=1.59 b)2NO + H2O ---->N2O + 2OH- E=x c)2H2O---->2H+ + 2OH- E=0.826 (calculated...

Homework Statement If E°(Fe2+/Fe) is x1 and E°(Fe3+/Fe) is x2 then find E°(Fe3+/Fe2+) 2. The attempt at a solution We need E for Fe3+ + e ----> Fe2+. We are given Fe2+ + 2e----->Fe is x1. Reversing will give Fe--->Fe2+ + 2e (-x1)...(i) also, Fe3+ + 3e----->Fe is x2, ...(ii) multiply (ii) by 2...