In electrical engineering, ground or earth is the reference point in an electrical circuit from which voltages are measured, a common return path for electric current, or a direct physical connection to the earth.
Electrical circuits may be connected to ground for several reasons. Exposed conductive parts of electrical equipment are connected to ground, so that failures of internal insulation which create dangerous voltages on the parts which could be a shock hazard will trigger protective mechanisms in the circuit such as fuses or circuit breakers which turn off the power. In electric power distribution systems, a protective earth (PE) conductor is an essential part of the safety provided by the earthing system.
Connection to ground also limits the build-up of static electricity when handling flammable products or electrostatic-sensitive devices. In some telegraph and power transmission circuits, the ground itself can be used as one conductor of the circuit, saving the cost of installing a separate return conductor (see single-wire earth return).
For measurement purposes, the Earth serves as a (reasonably) constant potential reference against which other potentials can be measured. An electrical ground system should have an appropriate current-carrying capability to serve as an adequate zero-voltage reference level. In electronic circuit theory, a "ground" is usually idealized as an infinite source or sink for charge, which can absorb an unlimited amount of current without changing its potential. Where a real ground connection has a significant resistance, the approximation of zero potential is no longer valid. Stray voltages or earth potential rise effects will occur, which may create noise in signals or produce an electric shock hazard if large enough.
The use of the term ground (or earth) is so common in electrical and electronics applications that circuits in portable electronic devices such as cell phones and media players as well as circuits in vehicles may be spoken of as having a "ground" connection without any actual connection to the Earth, despite "common" being a more appropriate term for such a connection. This is usually a large conductor attached to one side of the power supply (such as the "ground plane" on a printed circuit board) which serves as the common return path for current from many different components in the circuit.
I am researching ground source heat pumps, however I do not completely understand how they work.
I understand that a pump uses a small amount of electricity to pump heated ground water or an antifreeze solution through the a system of piping in the ground to transfer heat from the ground to a...
Calculus based course, this is from the "linear momentum of a system of particles" section.
I've attached a rough sketch of the graph from my textbook. The main points of the graph are this, it's a parabola, at T=0 and T = 4.5, P(momentum) = 6. At T= 2.25 (maybe) it bottoms out. I say maybe...
Has war gotten too easy for the nation?
We can maintain two wars at a time without any really serious impact on the average American.
We are in a time and age when the US (and other world powers) maintains a large enough volunteer army that we can declare and maintain a war without the...
Homework Statement
A ball is thrown at a velocity of 10 m/s, at an angle of 30° from horizontal and released 2 m
above the ground. What will the magnitude of ball’s resultant velocity be at the moment of
impact with the ground?
Homework Equations
Vf2 = vi2 + 2as
The Attempt at a...
Ok so I've been wondering, how is it that physicist's EXPERIMENTALLY determine the ground state configuration of electrons in a particular atom? In other words do they use emission spectra/thermodynamic calculations/etc?
Also, if ground state represents an atom's minimal energy state, which...
When the grounds are different at source and destination, how do you connect the signal source to your circuit?
I know there is a difference in the ground potential of source and destination. But is this treated as noise or just an additional voltage that adds with the source signal?
I thought...
Homework Statement
A particle is prepared in the state \psi (x) = \frac{1}{\sqrt{L}} in a region 0 < x < L between two hard walls (particle in a box). Calculate the probability that the particle is found in the ground state when its energy is measured.
Homework Equations
This question...
In the double slit experiment the electron can go through either slit. As long as it is not observed there is an interference pattern as the two possibilities superimpose. The common conclusion to this is that the electron goes through both slits.
Is there a parallel with the ground state...
I am confused about this example circuit (attached) where the Gate it connected to Ground.
I thought in order for current to flow in a MOSFET (i.e. NMOS) a positive gate voltage (Vg) AND Vds (drain to source voltage) needs to be applied. If Vg = 0, how is a channel created in order to allow...
Homework Statement
I am doing an experiment to find the difference in photosynthesis between different areas of grass.
I have and am taking more measurements. But essentially I need to convert the data I have into a flux per area over time.
the data logger records the data of CO2...
In electronics it is customary to define the potential of ground (thinking of the Earth as a large conductor) as zero. Is this consistent with the fact that the Earth has a net electric charge that is not zero?
I am confused about the definition of ground state and its characteristics. For a field in spacetime do we mean the ground state to be the minimum of the potential or minimum of the total energy? Specifically what is the momentum four vector of the ground state ( p^{\mu}=(...) ) for a massive...
How to show the ground state is orthagnol with the first in a quantum harmonic os...
Homework Statement
This is a revision question for an upcoming quantum mechanics exam, that i am stuck on. Any help or idea at how to approach the question would be greatly appreciated, i get the feeling...
Homework Statement :
the binding energy for the electron in the ground state of hydrogen-2 is 13.6ev
what is the corresponding mass defect of the hydrogen atom in amu (atomic mass units)
not sure if you need atmoic mass of the hysgrogen atom its given to be 2.014102u
Relevant equations:
not...
please help me ,i have a project which i m not easy with can anyone help me in designing a a vapor compression cycle for cooling in the summer and if desired heating in the winter,
and a ground source heat pump for cooling in the summer and if desired heating in the winter.
A particle is in the ground state in a one-dimensional box given by the potential
v(x)= 0 for 0<x<a
v(x)= inifinity other wise
A small perturbation V = V(0)x/a is now introduced. Show, correct to first order in perturbation theory, hat the energy change in the ground state is V(0)/2...
How can I tell, with an electronic configuration, if an element is in ground or exited state? Also, how can I determine what element it is if it uses a noble gas shortcut? I assume I find the noble gas in brackets, count the atomic number, add it to the elec config outside of the brackets, and...
im looking for the 3 principals i need to be employ in determining the electronic structure of the ground state of an atom
Ive got Paulis exclusion principle where no 2 electrons in an atom can occupy the same quantum state and hunds rule of the total spin of the electrons always has it...
How many electrons in the ground state of a Hg atom can have the quantum number ml = +1?
The way I am trying to figure this out is as follows..
Electron configuration for HG is..
[Xe]6s^2 5d^10
n=6
l : ml
0: 0
1: -1,0,1
2: -2,-1,0,1,2
3 -3,-2,-1,0,1,2,3
4 -4,-3,-2,-1,0,1,2,3,4...
Homework Statement
A soccer ball is kicked at an angle of 64° to the horizontal with an initial speed of 18 m/s. Assume for the moment that we can neglect air resistance.
Homework Equations
For how much time is the ball in the air?... Seconds
(b) How far does it go (horizontal distance...
It was released from a height of 1 meter above the surface. Describe the motion of the Earth from the moment I released the object in a realistic way. Order of magnitude estimates are ok. but you have to justify those approximations in a reasonable way.
Hint: This problem may look rather...
Homework Statement
Why is the ground state always symmetric and first excited state anti-symmetric?
OR Why does the ground state always have no node and first excited state has one node?
Homework Equations
The Attempt at a Solution
I want to construct the ground state wave function of orthohelium.
Here is my reasoning, please let me know if I am correct or not.
I forgot to add that for this post I am ignoring the electron-electron interactions.
Orthohelium has the triplet spin state which is symmetric. Because the total...
Homework Statement
2 electrons are in a box of length L. Ignoring Coulomb force, 1 and 2 are labels for the electrons and m is the mass of an electron. What is the ground state and 1st excited state for the energy and wavefunction for the two electrons? Is there more than one wavefunction...
The velocity of a skydiver falling to the ground ...
Homework Statement
SORRY FOR SO MANY QUESTIONS! I'VE BEEN WORKING THROUGH EACH OF THESE UNTIL I'M COMPLETELY STUCK, SO DON'T THINK I'M JUST TRYING TO SUCK ANSWERS OUT OF YOU FOLKS!
The velocity v(t) of a skydiver falling to the ground...
is the principle how an aircraft move ahead in ground similar to how a spacecraft moves ahead in empty space?
in the ground air is propelled backward and in space since it has no air, small explosion pushes the spacecraft ahead.
Newtons third law.
i understand in the case of...
My girlfriend recently took a physics exam, and she was confused about why she got one of the problems wrong. She asked me hoping I could clear it up. Heres my attempt
Homework Statement
Three Identical balls are thrown from the top of a building, all with the same initial speed. Ball A is...
If I buy a sirloin patty to make a burger, is that better for me than ground chuck? Also if I pressed it between paper roll to get the grease off does that significantly decrease the fat content? I like making my own burgers and have rationalized this as a healthier option than going to burger...
Homework Statement
a dam of height H has a hole half way down to the base. how far outward from the base does the stream hit the ground?
Homework Equations
The Attempt at a Solution
i think you have to use bernoulli's equation right?
first find velocity then distance x right?
If initial vetical velocity is zero, at what time and how fast does a skydiver hit the ground? Assume that g=10m.s^-2
Given that:
y' = -gt + A y' is the vertical velocity
y = -(1/2).g.t^2 +At +B y is the distance above the ground
In order to...
I'm so over my head that I don't even know how to ask this, but here goes...
The accelerometer in my device (an iPhone) gives an x,y,z vector that points to Earth. I'm using these values to determine the angle of the device relative to the horizon. Visualize a user aiming the device at a...
Homework Statement
State wether atom is in ground or excited state.
Homework Equations
A.1s22s22p3
B.1s22s22p63s23p64s23d104p55s24d7
C.1s22s22p63s23p64s23d6
The Attempt at a Solution
A. Ground because all are filled in order.
B.Excited because the 5s sub-shell isn't quite...
Hello all
I work at a BC Ski-hill... what I need is a method to quickly but accurately measure the depth of dense snow (man-made snow, some might call it ice). Traditional method of mechainically boring through to ground is slow, inaccurate & messy. New GPS based methods require detailed gps...
I am an A-level teacher so I don't want an answer in terms of anything too complicated (for my students!)
The hydrogen atom has a ground state energy of -13.6eV. I am happy with this.
This means that the electron needs 13.6eV of kinetic energy in order to become free of the nucleus...
Homework Statement
You have a solid, homogenous ball with radius R. Before falling to the floor, its center of mass is at rest, but it is spinning with angular velocity \omega_0 about a horizontal axis through its center. The lowest point of the ball is at a height h above the floor. When...
Suppose a 136 kg manhole cover is launched 50 feet in the air. What is the speed of the manhole cover when it hits the ground on its descent, in m/s and mph?
I converted 50 feet to 15.24 meters, but I do not know what equation to use here. I understand that acceleration due to gravity is...
Homework Statement
The Egyptian's sled system had a rather high coefficient of static friction (0.7) but a much lower coefficient of kinetic friction (0.3) How much force is required to start a block moving on level ground?
We know the block is 1980 kg
and after that:
Assume that one...
In the short time I've been here I've already noticed this forum seems to lack a good definition of electrical ground or earth, posters seem to mean different things when they use it.
Sorry if this is the wrong place to air this but it seems to have popped up in several different places in...
Homework Statement
In a typical lightning strike, 2.5 c flows from cloud to ground in 0.20 ms. What is the current during the strike?
Homework Equations
I = Q/t
The Attempt at a Solution
The reason I keep getting this wrong is because it says I am rounding something off wrong. I...
Hi, Some of the ICs for a portable device I'm making need to be attached to ground. However, the device needs to be wireless so I can't ground it the way we usually do. Is there any way around this, such as a circuit that could somehow act as ground? Thanks.
Assume 2 bullets-- Exactly the same outside size and dimensions, Exactly the same velocity in OUR atmosphere.
One Bullet weighs more than the other--
You shoot them straight into the air-- which one hits the ground first?
How about if you shot them horizontally?
Is there any webiste...
Homework Statement
when using E=(h(pi)n)^2/(2mL)
h=h bar m= mass of particle L= length
this may be a dumb question but is the ground state 0 or 1 for n
n=0,1,2...
Homework Statement
A model rocket initially at rest on the ground is fired vertically upward, and the engine thrust produces a constant acceleration a = 40 m/s2. After running for 2.5 s the engine is cut off and then the rocket is in free fall. (a) Find the maximum height that the rocket...
A canister is dropped from a helicopter 500m above the ground...
A canister is dropped from a helicopter 500m above the ground. Its parachute does not open, but the canister has been designed to withstand an impact velocity of 100m/s. Will it burst or not?
I did the problem, but the back of...
Calculating Speed of Falling Banana - "Just Before" it Hits Ground?
Homework Statement
"A monkey drops a banana. Its weight is 1N. It falls 3 metres to the ground. What is the speed of the falling banana just before it hits the ground?"
Homework Equations
Not sure, but I'm guessing I...
Homework Statement
Two neutral spinless particles of mass m are gravitationally bound to one another. What is the ground state energy of this two-particle gravitational atom?
Homework Equations
The Attempt at a Solution
So, it's a two particle system, but
H_{total} = H_1 +...
Homework Statement
hello:D I have a pole (no associations!) and I am leaning it over ground that it stands making a angle of \phi between ground and pole length. What are the forces working in down finish of this pole, the one who is going vertically down, and going horizontally? thanks for...
Hi,
i worked through several examples where the ground state energy of a particle in an arbitrary potential V(r) is estimated with Heisenberg's uncertainty relation.
In these examples they prepare the Hamiltonian for the particle. For example the Hamiltonian for a particle in a harmonic...