Potentials Definition and 244 Threads

Is Fe2+(aq) capable of reducing Sn2+(aq) to Sn metal? The standard reduction potentials from my book are -0.14 for Sn2+ and -0.44 for Fe2+ Because Sn has a more positive Epot it has a greater tendency to be reduced. So add the Epot up: -0.14 + 0.44 (oxidation)= 0.3. It's positive...

Homework Statement A rectangle has sides of length 5cm (right and left) and 15cm (top and bottom). Top left corner has charge (q1) = -5uC Top right corner has charge A = ? Bottom left corner has charge B = ? Bottom right corner has charge (q2) = 2uC a) What are the electric...

What are the cell potentials of the following? 1) ZnSO4 (1M) & CuSO4 (1M) 2) ZnSO4 (1mM) & CuSO4 (1mM) 3) ZnSO4 (0.1M) & CuSO4 (1M) I tried using the nearst equation and I keep getting that they are all the same value of +1.10V

I suppose I could've equally well posted this to the math forum, but here goes... One often sees the two-body potential f(r1, r2) being reduced to to f(r12). Can this be done in a more general case (can n-body potentials be reduced to just the distances between all the particles, e.g. f(r1...

Homework Statement Consider a neuron with resting potential of -65 mV and threshold of -55 mV. It receives two synaptic inputs with similar synaptic conductances, one with reversal potential of -10 mV and the other with reversal potential of -58 mV. Draw the predicted postsynaptic...

If we knew the four momentum of a neutrino should we then be in position to calculate whether the gravitational potential of our galaxy might "bind" that neutrino? Thank you for any thoughts.

Homework Statement Calculate the potential of a Zn^2+/Zn and Ag^1+/Ag couple. Homework Equations Zn^2+ + 2e^1– ⇌ Zn E= –0.76 V Ag^1+ + e^1– ⇌ Ag E= +0.80 V The Attempt at a Solution First I know to multiply the silver half reaction by...

I'm reading through the Introduction to Quantum Mechanics book by Griffiths (2nd edition) and it is describing delta-function potential wells. When it describes how to find bound states the energy is E < 0 (negative) in the region x < 0 (negative). It says the general solution is: \psi (x)...

A hollow spherical conductor of radius 3.00 cm has 6.00 nC of charge distributed uniformly over its surface. (a)What is the electric potential at the center of the sphere(in volts)? (b) If the conductor is solid rather than hollow, what is the potential at the center of the sphere? I know...

Does anyone know how either Lienard or Wiechert justified the (1-v/c) factor that appears in their potential formula for a moving charge?

I have a problem. I am trying to selfteach myself QM but I got stumped with this. Basically, in the issue of 1D step potentias, I know that you have to divide the problem into regions and solve the schrodinger equation for each one. However, when you solve it, you always get two solutions due...

I'm trying to find a divergenceless vector field based on its curl, and discovered that I could use a http://en.wikipedia.org/wiki/Helmholtz_decomposition" , and the article I found on this didn't make much sense to me. First, can someone confirm that the dimension referred to in the...

Hi All - Let's say I have a potential energy surface with two minima, one higher than the other. We will label the higher minima B and the lower minima A. Each potential well can be approximated as a harmonic potential with force constants kA and kB for wells A and B respectively. How small...

Homework Statement A uniform line charge of density pl = 1nC/m is arrange in the form of a square 6m on a side. (In the z plane) Find the potential at (0,0,5) m Answer:35.6 V Homework Equations R = The distance from the line to the point (0,0,5) dL = ax dx + ay dy + az dz The...

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Homework Statement Two capacitors of 2.0F and 5.0F are connected in series; the combination is connected to a 1.5 volt battery. What is the charge stored on each capacitor? What is the potential difference across each capacitor? Homework Equations C = Q / (Delta)V The Attempt at a...

Explain why cell potentials are not multiplied by the coefficients in the balanced redox equation. (Use the relationship between delta G and cell potential to do this.) i know that cell potential is an intensive property but i don't know how to explain why you don't multiply the the cell...

Homework Statement A long coaxial cable carries a volume charge density rho=alpha*s on the inner cylinder (radius a) and a uniform surface charge density on the outer cylindrical shell (radius b). This surface charge is negative and of just the right magnitude so that the cable as a whole is...

Homework Statement Consider the following arrangement of potentials and a test charge (not pictured) located at infinity. - To which location will a test charge of +3 microColumbs travel? The potentials are as follows: (-1V) top left (-7V) top right (+1V) lower left (+4v) lower...

Im doing some study on scalar and vector potentials in the area of electromagnetics, and the author of the book derived this equation \vec{E} = -j\omega\vec{A} - \nabla\phi where \vec{A} = vector potential and \phi = scalar potential and \vec{E} = time harmonic form of electric field...

Homework Statement A particle of mass m and E<V0 approaches from the left and encounters a potential barrier, assume the amplitude of the incoming particle is A. Write the time independent wavefunction for x>0 and x>0 at t=0 E is definite. Find the reflection coefficient of the particle...

Homework Statement There are a couple of introductory questions that aren't relevant to the last parts then it says: (d) If the current density is time independent and divergence free, show that the Maxwell Equations separate into independent equations for E and B. (e) Express E in...

Consider 3 charged spherical shells A, B, C with charges q_A, q_B, q_C and radii r_A<r_B<r_C V_A=\frac{1}{4\pi\epsilon}[\frac{q_A}{r_A}+\frac{q_B}{r_B}+\frac{q_C}{r_C}] V_B=\frac{1}{4\pi\epsilon}[\frac{q_A}{r_B}+\frac{q_B}{r_B}+\frac{q_C}{r_C}]...

I'm trying to get a picture of magnetic potential, as in how to relate it to spin precession. (So have I got the right picture so far?) Classically, B is measured as the derivative of curl (which is a circulation integral) "around" a conducting current (that is, perpendicular to the direction...

Hello! I'm trying to grasp the "intuitive" meaning of the thermodynamical potetials E,F,H and G, or at least of their connections. As in other threads before mentioned, I learned that you can't real.y give an meaningful definition of energy , so I assume for the other potentials this is...

Starting from the equation dE=tdS-PdV+\mu dN It is straightforward to derive all 8 possible thermodynamic potentials. My question is the following: Why are the only important potentials Entropy Helmholtz free energy Enthalpy Gibbs free energy Grand potential ? Why aren't the other three as...

My electrodynamics lecturer was talking about how potentials are arbitrary and that's why we have different gauges. I'm not too sure about how potentials can be arbitrary. Up to a constant? How? Cheers,

Excuse me but, this is a rough translaton from a Portuguese homework. Also, excuse me for my lack of knowledge in some physics, I do a programming course and one of the teachers said we had to know about this. Homework Statement http://img181.imageshack.us/img181/7084/87202322av0.jpg...

Hi, Just having a little trouble understanding the concept of standard cell potential...what is it exactly? I understand that it is compared to a reference potential of 0 for the reaction 2H+ + 2e- -> H2(g). But what does it mean when a given reaction has positive potential (other than the fact...

Homework Statement Suggest why manganate(VII), rather than dichromate(VI) is used to titrate with Fe(II) in volumetric analysis. The Attempt at a Solution i have figured out 2 possible answers but both may not be correct... 1. the colour change is sharper with manganate (purple to...

Homework Statement The general gauge transformation in electrodynamics is {\bf A}' = {\bf A} + \nabla \lambda and \phi ' = \phi - {{\partial \lambda}\over{\partial t}}. In the Lorentz gauge, we set \nabla . {\bf A} + {{\partial \phi}\over{\partial t}} = 0 . My question is: Is the...

Hello: There is a well known theorem which asserts that every attractive 1D potential has at least one bound state; in addition, this theorem does not hold for the 2D or 3D cases. I've been looking for a proof in my textbooks on qm but I've been unable to find it. Can you help me out? Thanks!

I can appreciate the degeneracy of an infinite cubical well, in which there are three different directions, and hence three different separation constants from Schrodinger's equation which determine three separate n's (for lack of a better word.. principal quantum numbers, i suppose. it really...

Homework Statement Consider two "solid" conducting spheres with radii r1= 4 and r2= 1. I.E., r2/r1= 1/4. The two spheres are separated by a large distance so that the field and the potential at the surface of sphere #1 only depends on the charge on #1 and the corresponding quantities on #2...

hello, I've just gone through a derivation using the vector potential A, and using the equation derived (a wave equation) which arises from using the lorentz gauge, it is applied to the problem of a current sheet in the xy plane, located at z=0 with current in the x direction only. the current...

Hey... I have a quick question for you guys about electric potential. I have a spherical shell with a constant charge distribution. The total charge(Q), along with the shell's radius is given. Also, V(infinity) is defined to be 0 in this case. I'm told to find: a. The potential at r = the...

Homework Statement Griffith's problem 10.8 Show that retarded potentials satisfy the Lorentz condition. Hint proceed as follows a) Show that \nabla\cdot\left(\frac{J}{R}\right)=\frac{1}{R}\left(\nabla\cdot\vec{J}\right)+\frac{1}{R}\left(\nabla '\cdot\vec{J}\right)-\nabla...

I'm kind of confused as to how to determine when a vector field is conservative. For example, if we consider the following scalar field: \varphi = arctan(\frac{y}{x}) We see that the gradient is: F = \nabla\varphi = \frac{-y i + x j}{x^{2} + y^{2}} However, F is not a conservative...

Homework Statement 3 equal point charges, each with charge 1.55 microColoumb, are placed at the vertices of an equilateral triangle whose sides are of length 0.100 m. What is the electric potential energy of the system? (Take as zero the potential energy of the three charges when they are...

Homework Statement There is a +1 micro-coulomb charge at the origin and a -3 micro-coulomb charge at 2 meters away along the x-axis. I am suppose to find the change in Voltage if second charge is moved to 4 meters away from the origin. Homework Equations I am thinking of using delta V=...

Homework Statement Hi all. Please take a look at: http://books.google.com/books?id=9p6sUTxUoZ0C&pg=PA417&lpg=PA417&dq=%22seek+a+vector+potential+that+is+parallel&source=web&ots=peoLUp4z_M&sig=vaRVDMazSj10x0k4v4iGKCHni0o What do they mean by that hint? The Attempt at a Solution...

Homework Statement In its resting state, the membrane surrounding a neuron is permeable to potassium ions but not permeable to sodium ions. Thus, positive K ions can flow through the membrane in an attempt to equalize K concentration, but Na ions cannot. This leads to an excess of Na ions...

Homework Statement I want to calculate the lienard-wichert vector potential, based on the retarded potential expression given in Heald-Marion (classical electromagnetic radiation). Homework Equations I get: A=v\Phi, where \Phi is the lienard-wichert scalar potential and v is the charge...

Hi, Can anyone help me to understand the following please? If a potential is symmetric does this mean that the eigenstates are either symmetric or antisymmetric? Is the ground state always symmetric and the first excited state always antisymmetric? Thanks!

If I have some arbitrary Thermodynamic system, and I want to find the equilibrium state what do I do? Lets say that I know Internal energy: U(S,V) Helmholtz free energy: F(T,V) Enthalpy: H(S,P) Gibbs free energy: G(T,P) (I omitted the dependence on particles N) I've been...

yes ------Is Ni2+(aq) capable of oxidizing H2(g)? no -------Is Fe2+(aq) capable of reducing VO2+(aq)? no -------Is Cr3+(aq) capable of oxidizing Fe2+(aq) to Fe3+(aq)? yes ------Is Sn2+(aq) capable of oxidizing Fe2+(aq)? yes ------Is Fe3+(aq) capable of oxidizing Sn metal to Sn2+(aq)...

Homework Statement The first ionization potential of potassium (Z=19) is 4.34eV, and the 4p--->4s transition occurs at approximately 768nm. Use this information to find the values of the quantum defects \delta(0) and \delta(1) for potassium, and hence to estimate the wavelength of the 6p--->4s...

Homework Statement 27 drops of salt water with same radius, are each charged to a potential of V volts. They are made to coalesce into a single drop. How is the potential of a new drop compared to the potential of the original drops. Homework Equations V ( potential ) = k* q/r...

Homework Statement A magnetic field of a long straight wire carrying a current I along the z-axis is given by the following expression: \mathbf{B} = \frac{\mu_0I}{2\pi} \{\frac{-y}{x^2+y^2} \hat{x} + \frac{y}{x^2 + y^2} \hat{y} \} Find two different potentials that will yield this field...

Homework Statement So, first of all, here is a drawing of a circuit: http://img253.imageshack.us/my.php?image=hexabj4.jpg The resistance of each hexagon wire is r. I need to find the resistance of this circuit when it is connected to the source with points A and B. I know that in...