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 Where a real ground connection has a significant resistance, the approximation of zero potential is no longer valid.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.
A ball has a mass of 240g. (which would be 0.24kg?) is moving through the air at 20.0m/s with a gravitational potential energy of 70J. With what speed will the ball hit the ground.
Equations:
Ek=mv^2/2 (kinetic energy)
Eg=mgh (Gravitational potential energy)
Ek=mgxdisplacement (if you...
Hi all, this is my first post on Physics forums so I apologise in advance if I have posted in the wrong section etc. This is something that I have been trying to figure out for nearly a week now! I have modeled a vehicle in Solidworks, specifically an external roll cage, and hope to conduct a...
Homework Statement
A ladybug with a velocity of 10 mm/s [W] crawls on a chair that is being pulled with a velocity of 40 mm/s [40 degrees N of W]. What is the velocity of the ladybug relative to the ground?
Homework Equations
The Attempt at a Solution
finding the y-component...
Homework Statement
For potassium in ground state configuration (Z=19) how would you expect the energy of the least tightly bound electron to compare with the energy of the electron in hydrogen excited to a state of the same principal quantum number n. Explain your answer.
Homework...
I have a device in a DC circuit that calls for decoupling capacitors on VIN and VOUT. The circuit is powered by two batteries in series. The above device is hooked up in parallel to the second battery with the device ground connected to the node shared between the two batteries like so...
Ok, so I've been wrestling with the concept of ground for the past two weeks. I'm in an electrical engineering program at college, and let me preface this by saying I have no difficulty dealing with ground in a practical sense and understand its general function very well. That being said, I've...
The "stand your ground" laws
Considering the current controversy in Florida over the death of a minor and what defense the killer may (or may not) use, here is some information from Wikipedia about the law:
“A “stand-your-ground” law states that a person may use deadly force in self-defense...
Homework Statement
For archery practice, a knight's squire drops sandbags from a 12.0 metre tower. At exactly the same time the sandbag is dropped, the knight shoots an arrow up at the sandbag from the base of the tower. If the arrow strikes the sandbag at 1.1 seconds, calculate;
a) how...
Hello
My question is about the ground state of vibrations for a solid. I'm working with graphite and have found out that for k=0 (The Gamma symmetry point), the vibrational modes can be decomposed into irreducible represenations in the following way
Vibration = 2 * E1u + 2 * E2g + 2 * A2u...
When the Sun is directly overhead, a hawk dives toward the ground with a constant velocity of 4.15 m/s at 54.5° below the horizontal. Calculate the speed of her shadow on the level ground.Homework Statement
Homework Equations
vxi=vicosθ vyi=visinθ (i think)
The Attempt at a Solution...
Homework Statement
Consider the Hydrogen atom in a magnetic field of 2T. If the atom is in its ground state (orbital angular momentum L=0):
(a) Write down the magnetic moments of the proton and the spinning electron. [1]Homework Equations
I am aware that the magnetic moment μ =...
Hi all,
I am trying to interface two separate boards. the power supplies of both the boards are different. One board would act like an output board in the sense it gives either 0V or 24V and the other acts as input board accepting 24V or 0V (any voltage in between as well). Now main doubt is...
Homework Statement
A wheel with a radius 50 cm is rolling along the ground at 10m/s[E]. That is, the centre point of the wheel is moving at 10 m/s [E].
- What are the velocities of the top, bottom, front, and back points of the wheel, relative to its center?
- What are the velocities...
Howdy -
I'm looking for a way to approximate the anchoring strength of a partially buried concrete caisson (pier). It would be used for anchoring a guy wire coming into it at about 45-degrees from above. Most of it's in the ground, a few inches sticks above where the cable fastens to it...
Homework Statement
The flag pole is 10m tall. The base of the pole has rusted and the pole topples over. What is the time taken for the pole to hit the ground?
s = distance = 10m
u = initial velocity = 0 m/s
v = final velocity = unknown
a = g = acceleration due to gravity = 9.81 m/s2...
The basic concept of a circuit kind of eludes me:
Where do neutral/ground/negative wires ultimately go to (i.e. what must the 'thing' they connect to be)? Is it always ultimately the Earth or must it be connected to the actual power generation itself somehow?
Example: Could I take a...
I'm currently doing a Lab in my University Physics class to calculate the initial velocity of a ball right as it's fired from a cannon. I'm not particularly looking for the answers, just the equation needed (i think I copied the equation from the professor incorrectly).
Here's what I have...
Hi,
I generally work on embedded boards so i always had this doubt generally in any embedded board with micro controller the pins on the micro controller are located very very close, so if i am trying to see the voltage or some waveform on any of the pins using oscilloscope or multimeter and...
V^2=Ae^-2kx - g/k (upward motion)
V^2=g/k - Be^2kx (downward motion)
Use the above result to show that , when the bullet hits the ground on its return, the speed will be equal to the expression
Vo Vt / (Vo^2 + Vt^2)^0.5
In which Vo is the initial upward speed and Vt= (mg/C2)^0.5=...
Hello guys,
It's a while I've hang around. Now that I've already finish undergrad, I would like to know about postgrads:
1. I've heard about publishing at Q1 journals (I assume quartile 1..). Is this an internationally 'adapted' term? So I've heard that Q1 papers will grant you better...
Hi,
In one of my advanced quantum mechanics classes, the instructor posed a problem, namely to show that the ground state of a one dimensional quantum harmonic oscillator is unique, without getting into differential equations.
I know that the equation
a\left|0\right\rangle = 0
when...
1. A bullet of mass 0.0020 kg and traveling at 300 m/s strikes the center of a 3.0 kg block of wood which is sitting on a fence post. The block of wood is 2.0 m above the ground.
I got the velocity using the eq (m1v1 + m2v2)/Mtotal = 0.2 m/s [correct if incorrect please]
I then got the...
Homework Statement
A sphere of a mass m and radius R is fired straight up with a speed v0
a) What is its speed when it hits the ground (Include quadratic air resistance but ignore linear air resistance
b) Evaluate the result for part (a) with R = 0.2c, v0 = 1.3m/s and m = 100mg
I am...
Several years ago I got in a big argument with the folks that wired a new control room (a project I had nothing to do with, but jumped in as a concerned employeed).
These guys provided 3-terminal power outlets, but on each terminal they connected the ground to the return, based on the...
Homework Statement
A spacecraft approaches the surface of an unfamiliar planet and finds that the pressure of the atmosphere 50 km above the surface is 2.0 × 10^5 Pa. As the spacecraft descends, it is found that the pressure of the atmosphere 40 km above the surface increases to 5.0 × 10^5...
Metal detectors for searching metals in the ground
How they work in one sentence explanation?
and second,
I've seen some frequency of about 8 kHz mentioned,could that be any possible health risk?
Please discuss, thanks.
when a continuous symmetry is broken, we say that the ground state is just one of the possible ground states, and there is no energy cost in moving from one to the other..
why doesn't the state keep changing with the slightest perturbation (production of goldstone boson).
why don't we have a...
can "light" excite an electron from ground state to a higher state?
An electron of a particular atom can absorb a discrete amount of energy, leap to a new quantum level, and then jump back down to lower states (emitting photons). My understanding is that going from n=2 to the ground state a...
I've tried researching this question and I couldn't find a satisfying answer. How come the water on Earth hasn't been absorbed by the ground over billions of years? The Earth's water evaporate but get's replenished when it comes back down as precipitation. Is there a similar process that...
Hi friendz I have a problem.
If a block of mass m is placed over the wedge such that there is no friction then what is the acceleration of block
1with respect to wedge
2 with respect to ground
Pleas reply.
Thanks in advance.
My sir said that it is different.Is it so.
Homework Statement
How much energy (in kJ) does it require to remove an electron out of the ground state of hydrogen atom completely, according to Bohr?
Homework Equations
The Attempt at a Solution
I have a problem with an above-ground water tank supplying a pump on the ground, supplying a sprinkler system. When the pump turns off, the water doesn't stop due to the syphon effect. When I first installed the pump, I put in an adjustable sprink check valve after the pump, but it still leaked...
I recently had a discussion with a guy who believes that by putting a big slot in his PCB ground plane he will protect his analog domain from the noise originating in his digital domain. I don't agree with this view (hence the discussion), for various reasons, but to keep this post on point I...
I'm trying to follow a derivation of the ground state energy of Helium using perturbation theory. I've made it through most of the derivation but I'm stuck at the following integral
Homework Statement
Find the value of C where
C=\frac{1}{(4\pi)^2}\int...
Hi,
I am trying to understand the calculation of the characteristic impedance of a CPW ground. I need to get an analytical expression for the impedance. My first step was to read the book: "Coplanar_waveguide_circuits__components__and_systems"
Here is what I don't understand: the...
Hi,
If I have the Hamiltonian: H=(1/2)p^2+(1/24)\lambda(x^2-v^2)^2 what is the best way to find the ground state wave functions \psi(x) . I was thinking this sort of looks like the harmonic osscilator, so maybe a clever change of variables could do the trick? or some form of perturbation...
Homework Statement
Already it is on title !
Homework Equations
attachents provide the most relevant equations i could find.
The Attempt at a Solution
I have found some old books written in 1920 decade ,dealing with this subject,but the solution they provide seems very hard...
Homework Statement
A particle of mass m is confined to move in a one-dimensional "infinite" potential well defined by V(x)=0, |x|< or=a, V(x)=infinity otherwise. The energy eigenvalues are E(subscript n)=((n^2)(pi^2)(h-bar^2))/(8m a^2), with n=1,2,3,... and the orthonormal eigenfunctions are...
ANYS Static Structural, How to simulate 'ground"?
Hello all, first post.
I'm having trouble simulating a fixed support in only ONE direction.
For example, imagine a gigantic frame laid on the ground and you wanted to see the forces deflect from pulling up on one corner, (the ground...
Homework Statement
I have this question regarding how i would do the second part of this question as i already know how to do the first part ,but i can't seem to find an approach to the second."What is the speed of the stone at a height of 10m from the ground?"
A stone is thrown off the...
Okay so I've seen that some not all power supplies have a positive and negative side for the voltag output and in addition have a common ground connection, exactly what is that used for?
Hi all,
I was trying to find the time required for liquid ejecting from a hole in a tank to reach ground level. The equation given in one of the books is as follows:
t = √(2h/g) or sqrt of (2h/g).
where h stands for the height of hole in tank shell from the ground level.
This...
Question:
1. A clock is hanging on wall. length of minute hand is 16cm and the length is 8cm for the hour hand. The highest that the tip of the minute hand reaches above ground is 265cm.
a) What is equation of axis, amplitude & period in minutes of function that represents the tip of hour...
Building a wireless energy transfer systems with a transmitting and receiving antenna. I have encountered a problem with what appears to be a floating ground. Initial testing is done with a normal LED that will only light when I have my finger touching one of the leads on the LED. Further...
Hi
I noticed that certain workers were laying Pneumatic lines underground ( the lines will be covered with concrete) in a factory.
I have no idea how much the pressure would be , or what safety precautions they are undertaking.
The lines are used to power certain pneumatic tools ( Torque guns...
I had a curious thought today, here is my logic: Charged particles have E fields. Moving charged particles create B fields. Electrons are moving charged particles, oscillating in an atom. Therefore, I concluded that an atom must be creating an oscillating EM wave, even in the ground state.
But...