Can someone explain the Hall effect?
102156
A simple version of the Hall effect is to place a plate with a current flowing through it in a magnetic field. The charge carriers passing through the plate will be subject to forces from the magnetic field (so-called Lorentz force, which acts on any charges moving in a magnetic field), pushing them to one side or the other of the plate, creating some difference in electric potential (i.e., voltage) that can be measured. \n\nFrom the sign of the potential (voltage), one can infer what is the sign of the charge carrier (remember that up until the mid-1800s, it was not known if charge carriers were negative or positive and Benjamin Franklin guessed wrong, picking positive and we are now stuck with that convention).\n\nThe Hall effect is used to create very sensitive sensors for determining relative positions. Hall effect sensors  have found many uses, in antilock breaking systems, in automotive ignition systems, in fuel injector systems in engines, etc.\n\nThere is a related quantum version of the Hall effect called the Quantum Hall Effect, where the conductance (that is, how easy electrons are able to move through a material) associated with the Hall effect is quantized; that is, it only can take certain discrete values, at low temperatures. This quantum hall effect can be used to measure very fundamental quantities of matter very accurately, particularly those involved with the inner workings of a field called quantum electrodynamics (a subtle extension of quantum mechanics). \n\nThere is obviously a HUGE amount of material here, but this might get you started.
1088099
insulators ; conduction
606031
It's O.K. to stipulate there's no resistance - but not that the system can reach a static equilibrium state with no energy dissipation at all. The two assumptions are incompatible.\n\nIn the absence of resistance, the inductance, which can never be exactly zero even for a straight wire, would limit the current and also cause its direction to oscillate back and forth between the two capacitors until exactly 1/2 the original energy is lost through EM radiation. \n\nIf somehow there were no radiation, the system would keep oscillating forever with 1/2 the original energy being held in the magnetic field at the moment in each cycle when the capacitors were each exactly half charged. The rest of the time the capacitors would hold between 50% and 100% of the original energy.
866556
If the conductance band is very narrow, it results in a very high effective mass for the carrier.  This is because: giving velocity to the carrier increases its total energy.  If this total energy isn't within the band then the carrier can't be given it and so moves slowly.\n\nYour case would seem to be an N type good conductor,possibly a metal.
115800
I hope you are familiar with atomic theory if not get familiar and come back to this. as an electron moves it creates a wake much like a boat moving through water this wake is called a magnetic line of force. if a nother electron is encountered by this wake it will be influenced by it like a surfer on a wave. an electromagnetic fiel is the area of influence of these waves. in most materials the electrons are moving in many different directions, hence the sum field is random and weak. however if most of the electrons are coerced into a uniform movement the individual lines become coherent and combine to provide a polarised field with a stronger magnetic influence moving this fiel across an object will cause the electrons in it to surf and produce an electric current. however these surfing electrons will produce a magnetic field that is the opposite of the field they are surfing on.
1179277
the importance of physics?? it is very imp cos if there wasn't pysics we wouln't know how things work. there wouldn't be neither electricity nor magnetism. you wouldn't live as comfortable as you live today...is this enough? :)
370991
When a magnet rotates around a conductor, it generates a current in that conductor. \n\nCurrent itself is actually the electrons in the conductor moving. Some of this momentum for each electron is lost when it collides against an adjacent electron or in moving against the repulsive force between them. The sum total of all this energy lost by all the electrons is seen as heat and the conductor heats up.
866700
electricity produced due to flow of charges/electrons
343981
In two charged plates, other than between the plates (and the edge effects), are there any field line? \nYES! other field lines are between the outer sides of the plates(depending on the charges of the plates and the convention used for the direction of the flow). To prove this, just connect the outer sides of the plates by a wire through an amper meter and you will see the meter moving.\n\nWhy is the electric field constant everywhere in the space between parallel plates? \nThey are not unless the area of both plates is inifinte and that the two plates are parallel.  In this case, the 1) direction of the field is the same every where since by definition the plates are parallel and 2) the absolute value is constant.  If not, there will be a surface current and the current would make the entire electric field (its magnitude) to be constant over the entire surface.
712708
The movement of a hole in p-type semiconductor is in fact the movement of electrons sequentially filling a valence band vacancy.\nThis means that holes tend to move at a lower speed than electrons would in the same material with the same electric field applied.\nWe measure the effective mass of the hole by applying a field to the material and seeing how fast the holes accelerate (Newton's Law)\n\nIf you look at the characteristics of complementry transistors, which are being sold as matched pairs, you will see the extra mass of the hole manifests as an inferior characteristic in the ptype carrier transistor or FET.\n\nA p-type carrier is a hole in a semiconductor.\nA positron is a hole in space that can be filled by an electron.  The hole in space has a mass, velocity and the opposite quantum numbers of the electron.\nHoles and positrons are not the same animal!!!!!!
713269
Faraday's Law!\n\nMass Plated = t * I * MW / (n * F)\n\nt = time\nI = current (Amps)\nMW = mol weight of metal\nn = valence charge of metal\nF = Faraday's Constant (96,500 Coulombs/mol e-)\n\nSo....\n\nt = 2 days * 24 hours/day * 3600s/hour = 172800s\nI = 7.60 A\nMW = 51.94 g/mol\nn = 3 mol e- / mol M\n\nPlug it all in and you should get 235.62g of Cr.
57156
I was wondering myself.  So, when no one answered I decided to do some research.  I found several explanations that did not make sense.  But I did locate some credible sources.\n\nThe first reference gives technical information on encoding the magnetic strip.\n\nThe second provides confirmation that noise from scratches or defects in the magnetic strip induces spikes in the reader that can be misinterpreted as valid data.\n\nThe third provides an explanation in layman's terms that is consistent with the more technical explanations.  The following quote is from this source.\n\n"Let's just say that when you swipe the card through the reader, the magnetized particles in its stripe generate a signal with "ticks" in it at intervals that the machine is able to interpret as digital ones or zeros. A scratch or other defect in the magnetic stripe can cause a spike (i.e., brief fluctuation) in the signal that a too-sensitive reader will interpret as a tick, meaning that the encoded data will fail the parity check (the numbers won't add up right) and the card won't work. Wrapping the card in plastic increases the distance between the read head and the magnetic stripe, thus reducing the strength and crispness of the signal and smoothing out anomalous fluctuations. Behold, the card works."
25244
What type of resistance--thermal, electral, or what?\n\nBoth are generally determined by the bandwidth of free electrons if any are present.  In electrical, it can also deal with impurities in the material.  In thermal, it can have to do with the irregularity of the molecular structure, the density of the solid, and the heat capacity of the molecules.
1076485
i dont know much about physics but i did a search and this is what i got hope it has what you're looking for:\n\nhttp://science.electronicsinfoline.com/Physics/Electricity_and_Magnetism/
607179
a belt is driven across a surface rubbing the two together to make 'static', which is basically just free electrons. they collect in the big metallic ball, and when the potential is high enough between the ball and another conductor (or a conductor is brough close enough), the electrons 'jump the gap' to get to ground, and you see the big spark!\n\nWant to build one? Here's how:
31718
for an ohmic material:\n\nP=VI\nV=IR\nso\nP=I^2 * R\n\ncheers!
411386
photoelectric effect can be demostrated if u can excite an electron in a material so that it has enough energy to leave the matrial. i.e. E > (Evacuum-Ef). now u need to look at the energy of the free electron which can be found simply by putiing in through a magnetic field. the deflection will depend on the velocity and hence its energy. this excitation of the electron is done by electromagnetic radiation or light. this free electron is actually free and is not as that meant in semiconductors where free means that it is STILL in the material but free to move. moreover the "free" electron in a semiconductor, even if excited to a higher energy than the conduction band edge, will come down to the conduction band edge by various non-radiative process and than move. photoelectric effect can also be seen in semiconductors if the excitation is so high such that the electron leaves the material. this method is used to find the position of the fermi level.