Ground Definition and 921 Threads

Homework Statement For a hydrogen-like “atom” (e.g., He+ ion), with nuclear charge Ze, it is claimed that the the ground-state wavefunction is spherically symmetric and is given by ψ(r)=Aexp(−αr) , where A and α are constant. (a) Determine the normalization constant A in terms of α. (b)...

Hi everyone, I'm trying to implement the attached circuit. (the .txt is for http://www.falstad.com/circuit/) Since I only have a single power supply and I ultimately want to drive this with a battery I am powering the opamp with a virtual ground. Using a voltage divider to achieve this. Opamp...

When i take a coherent state ##|\alpha>## if ##\alpha -> 0## then the limit is the Fock state for n = 0. so ##|n = 0> = |\alpha = 0>## The problem is that they seem to have different http://www.iqst.ca/quantech/wiggalery.php: Where is the error? Thanks. Edit sorry, in the link the W function is...

Homework Statement Find the electric field between the conductor and ground. The conductor is at: Potential = +V0, radius a distance d from the ground plane. Homework Equations I used image theory to create a conductor at -V0 at distance -d from the ground plane. Laplace's equation: ∇2V = 0...

Greetings !New to the forums. Here expanding my concept of what AC Electricity is My question (correct me if wrong).. If AC power alternates between +,- at a rate of 60Hertz/second and negative is used as -earth- at the AC generator If the hot wire touches the ground would happen? (I think...

Hiya, I'm a bit of an intermediate in electronics and I am moving into oscillator territory and am thinking more about "ground" rather than "the negative side of the battery". Obviously, using -ve voltage as ground has some setbacks with dc-ac oscillators as current can only flow if there is a...

New to the forum :) We were (trying to) discussing this at work the other day. Consider a simple battery powered circuit, with a resistor and an LED. With a battery, current is "chemically produced" in the battery and flows from the positive to the negative pole, passing through the LED...

Notation: ##J^p## - ##J## the total angular momentum, ##p## the parity = ##+## or ## -. ## Ok so I'm given a diagram of energy levels, all have a ground state of ##0+##, except one which has a ground state of ##1+##. I'm askeed to indentify which set of energy levels belong to which nucleus...

I have a 3 conductor wire that are all wrapped in a foil shield with wire conductor, for a total of 4 wires. I am connecting the 3 inside wires to audio left, right, and ground. This is an unbalanced setup, right? Where/how do I connect the shielding? Do I connect both sides (i think no)...

Hi Physics Forums! The ground state electron is the largest negative value, but what does this mean? Does this mean that kinetic energy is a positive value above zero? It seems at the ground state, the electron might also have kinetic energy as it is moving around as well as potential...

Homework Statement A long, straight power line is made from a wire with radius ra = 1.0 cm and carries a line charge density λ = 2.6 μC/m. Assuming there are no other charges present, calculate the potential difference between the surface of the wire and the ground, a distance of rb = 22 m...

Homework Statement A car has four tires in contact with the ground each of which is inflated to an absolute pressure of 3.1×105Nm^-2. If a person of mass 82 kg gets into the car by how much will the total area of contact between the tyres and the ground increase assuming that the tire pressure...

I have several questions about poles and towers. a. Does all of transmission towers carries three-phase powers? Is there no transmission towers designated for single-phase? b. Does all towers are for transmission purposes only? Is there any towers in the world used for distribution instead of...

Hello All, I am pretty sure that when a nucleus decays via e.c. and goes to the ground state all of the excess energy is released with the emission of the neutrino but was wondering if anyone could confirm/give a reference for this. Thanks!

Homework Statement A lunar lander is descending toward the moon's surface. Until the lander reaches the surface, its height above the surface of the moon is given by y(t)=b−ct+dt2, where b = 770m is the initial height of the lander above the surface, c = 62.0m/s , and d = 1.02m/s2 . Part B...

Dear all, periodic DFT codes (e.g. VASP) effectively simulate an infinite crystal due to the periodic boundary conditions. However, the energy value that one obtaines at the end of a simulation if finite. Frankly, I'm quite confused right now. Is the energy to be understood 'per unit cell'...

Homework Statement Consider a one-dimentional particle in a box with infinite potential walls at x=0 and x=L. Employ the variational method with the trial wave function ΨT(x) = sin(ax+b) and variational parameters a,b>0 to estimate the ground state energy by minimising the expression E_{T}=...

Is it possible to sufficiently ground yourself just by touching the negative lead of a wire coming from a power supply once?

Homework Statement Two very long parallel wires 1.0m apart lie on the ground carrying currents 4.0A and 6.0A in the same direction. How far from the 4. wire are the magnetic field completely cancelled? 1.0m on the other side of the 4.0A wire, what is the magnitude of the magnetic field...

Hi guys! Suppose there's a particle in a box, initially in its ground state. Suppose that one chooses a system of coordinates such that the potential V(x) is 0 from 0 to L. Suppose that one suddenly perturbate the system at a particular time so that V(x) becomes 0 from 0 to 2L. I've calculated...

Homework Statement A worker lifts a 20.0-kg bucket of concrete from the ground up to the top of a 20.0-m-tall building. The bucket is initially at rest, but is traveling at 4.0 m/s when it reaches the top of the building. What is the minimum amount of work that the worker did in lifting the...

Homework Statement A body is dropped from a height ##h## with an initial speed 0, reaches the ground with a velocity of 3 km/h. Another body of the same mass was dropped from the same height ##h## with an initial speed 4 km/h. The second body will reach the ground with what velocity ? Homework...

Hey, I am new to this stuff and was just wondering if someone could help me i need to know what could i use to lift 180lbs about thirty centimetres off the ground, also this device has to be small but still powerful enough to lift the required weight i would appreciate any help i could get. Thanks

Hello everyone: I didn't have a complete view of the quantum field theory and cannot understand this question. We now there will always be fluctuation field in the universe which corresponds to the ground state energy 1/2hw of harmonic oscillator. In the free space, we will use box...

Homework Statement At t<0 a particle is in the ground state of the potential V(x)= \frac{1}{2} mw^2x^2 . At t=0 the potential is suddenly displaced by an amount x0 to V(x)= \frac{1}{2} mw^2(x-x_0)^2 . a) What is the probability of the particle being in the ground state; the first excited...

Hello, I am sure that this question has been answered on here before, but i could not find it. Why is the Earth ground, and where does the electricity go after it gets there. I understand that ground is potentially lower than that of the power company's production etc. but i am curious as...

I have read that, in the early days of the telegraph, two wires were used, but Steinheil, of optics fame, discovered that the circuit could be completed by 'earth return', using the ground as return ...conductor? That's my question. It's hard to believe that currents strong enough to operate...

Suppose you have the transition amplitude in the presence of a source <q''t''|q't'>_{f} To extract the ground state, we change the Hamiltonian to H-i\epsilon , because we can write: $$|q't'>=e^{iHt'} |n><n|q> \rightarrow e^{iE_0t'} |0><0|q>=<0|q>e^{iHt'} |0>=<0|q> |0 t'> $$ where only...

What exactly does it mean when we say that a conductor is grounded? I know it generally means that its potential is zero, but shouldn't the description of potential also give the location of a reference potential? For instance, if a conducting spherical shell is grounded, if its potential is...

If a voltage source is connected between a ground and a node of unknown potential will it be a super node. For example would the 5V source be part of a supernode?

From the ground state wave equation the most probable outcome of anyone measurement will be in the center of the atom, at the nucleus. The expectation value is found to be the Bohr radius. So does this mean that if you measure the position of an electron in a hydrogen atom in the ground state...

Hello,just seeing if someone can help me on here,i have a rc glider measuring 2200 mm on the ground,when in the air it measures about 35mm. Can the the height be calculated from these measurements.

Hi guys, so I've been given a physics question which is black magic to me, so I thought i will ask you for help :) Here is the question: A pile driver hammer of mass 170kg falls freely through a distance of 6m to strike a pile of mass 410kg and drives it 75mm into the ground. The hammer does...

This may seem like a really basic question (I'm teaching lower school science, and it's not my specialism!), but: What causes the force which balances gravity, which I think is called "ground reaction force?" All the descriptions I've seen say that the ground "pushes" up on a stationary...

Homework Statement A block on a ramp is held by a tension force parallel to the horizontal (not the ramp). If originally the tension force was parallel to the ramp, is the tension force when it was parallel greater, equal, or less than when it is horizontal? Homework Equations Trigonometric...

I now understand how the wavefunction graphs look from the hyperphysics: http://hyperphysics.phy-astr.gsu.edu/hbase/quantum/hosc5.html. However, what I fail to understand, is how the wavefunction equation was derived for the 1st excited state, from: ground_wavelength0 = (a/pi)1/4 e(-ax2/2)...

I am curious, if I were to draw a wave function, would one for ground state and one for excited sate be different? If different, could someone explain how and why? If you could, thanks!

Hello I been having a "debate" about the load on an engine when going max speed on a lake vs a lesser speed but on an incline.. Here is the basic jist of the discussion... We are talking about a 150HP snowmobile using a CVT at sea level with low snow conditions that is traveling across the...

Homework Statement Hello! I am trying to derive the ground state enegry of a hydrogen atom, and have come to U=\frac{-mk_{0}^{2}Ze^{4}}{n^{2}\hbar^{2}} Problem is, I know there should e another factor of 2 in the denomenator because I get the ground state energy of hydrogen as being 27.145eV...

Hi guys, I was working on a formula for the optimal angle for simple point-like projectiles free-falling under a uniform g-field but I got stuck. after a simple derivation , I obtained the following equation: R=(vcos(@)/g)(vsin(@)+((vsin(@))^2+2gh)^0.5) where R , @ , h are respectively the...

I am not talking about Digital circuit ground bounce on PCB. How do I simulate a Ground bounce for a system that runs on 220V AC. In real field conditions, the system might be connected to different grounds. How do i replicate this in the lab. Can I have a SPDT relay between GND1 & GND2...

http://forums.mikeholt.com/showthread.php?t=162981 I thought this would be a link worth sharing here on pf. We seem to have heated arguments going on this forum from time to time about which country has the best electrical system. There are some interesting things to read in the above link...

If I understand it correct during hammerthrow an athlete muscles cause Fcentripetal force on a ball and ball cause reaction Fcentrifual force on athlete. The athlete also cause Frotation on ball by rotating his body and ball cause Freaction on athlete. What would happen if athlete would try...

I have often wondered why conventional large wind turbines have evolved with their generators and gearboxes in the nacelle at the top of the tower where they are hard to reach and maintain. Despite this fact, I wish to believe that there may be benefits to a conventional horizontal shaft wind...

I was looking at this graph and wondering what the value of the graph would be before the engines turn on. Should it be 1 g-force or 0 g-force? (the "force" in g-force being a misnomer as it is a measure of acceleration, not force) Below are arguments for each: Why it should be 1 g-force: We...

I understand that in an electrical outlet, "ground" is wired directly from the outlet to the ground, whereas neutral is wired from all the outlets to the breaker box or wherever in the house, then to the ground, and that neutral is intended to carry current. That being said, I am confused...

Homework Statement A ball of mass 1kg is dropped from a height 1m . Estimate how long the ball is in contact with the ground in seconds ? Details and assumption Simplify the question by modeling the ball as an ideal spring of spring constant 100Nm . Take gravitational acceleration if...

Homework Statement A baseball is hit at ground level. The ball reaches its maximum height above ground level 3.1 s after being hit. Then 2.6 s after reaching its maximum height, the ball barely clears a fence that is 97.2 m from where it was hit. Assume the ground is level. a) How far...

In a past physics gre question (https://www.physicsforums.com/showthread.php?t=192334), we make use of the idea that the ground state energy of two ions that have spin is when the spins are aligned. However, the ground state of the helium atom is a spin singlet state, which is a linear combo...

So i am relatively new to electronics and i was wondering, on a circuit there will be grounds but its not an actual wire running into the ground, especially on small circuits in phones and stuff, so how is it grounded and what is used to ground it?