What is Faraday: Definition and 213 Discussions

Michael Faraday (; 22 September 1791 – 25 August 1867) was an English scientist who contributed to the study of electromagnetism and electrochemistry. His main discoveries include the principles underlying electromagnetic induction, diamagnetism and electrolysis.
Although Faraday received little formal education, he was one of the most influential scientists in history. It was by his research on the magnetic field around a conductor carrying a direct current that Faraday established the basis for the concept of the electromagnetic field in physics. Faraday also established that magnetism could affect rays of light and that there was an underlying relationship between the two phenomena. He similarly discovered the principles of electromagnetic induction and diamagnetism, and the laws of electrolysis. His inventions of electromagnetic rotary devices formed the foundation of electric motor technology, and it was largely due to his efforts that electricity became practical for use in technology.As a chemist, Faraday discovered benzene, investigated the clathrate hydrate of chlorine, invented an early form of the Bunsen burner and the system of oxidation numbers, and popularised terminology such as "anode", "cathode", "electrode" and "ion". Faraday ultimately became the first and foremost Fullerian Professor of Chemistry at the Royal Institution, a lifetime position.
Faraday was an excellent experimentalist who conveyed his ideas in clear and simple language; his mathematical abilities, however, did not extend as far as trigonometry and were limited to the simplest algebra. James Clerk Maxwell took the work of Faraday and others and summarized it in a set of equations which is accepted as the basis of all modern theories of electromagnetic phenomena. On Faraday's uses of lines of force, Maxwell wrote that they show Faraday "to have been in reality a mathematician of a very high order – one from whom the mathematicians of the future may derive valuable and fertile methods." The SI unit of capacitance is named in his honour: the farad.
Albert Einstein kept a picture of Faraday on his study wall, alongside pictures of Arthur Schopenhauer and James Clerk Maxwell. Physicist Ernest Rutherford stated, "When we consider the magnitude and extent of his discoveries and their influence on the progress of science and of industry, there is no honour too great to pay to the memory of Faraday, one of the greatest scientific discoverers of all time."

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  1. J

    Designing a Faraday Cage for Precision Resistor Network & DVM

    Hello I am building a Faraday cage, I cannot find any decent information on the designing one. I plan to use it to shield a precision resistor network and 8 1/2 digit DVM in order to measure Low Frequency noise of a HV power supply. I need to know what dictates the size of the "holes" in...
  2. Q

    Faraday rotation in plasma?

    I'm looking to find an expression for the Faraday rotation of a wave in a magnetized plasma, propagating parallel to a magnetic field. It's more math help than physics help I need here though. I know that I'll have to start with the dispersion relations for a right and left circularly polarized...
  3. H

    Some questions about Faraday heaping

    Here is a a simply description: When a container filled with mustard seeds(small sphere) is vibrated vertically with a frequency between 1 - 10 Hz,we see Faraday heaping occurs. I want to know how do I design a experiment to investigate this phenomenon? We have problems in...
  4. H

    Hot air gun, practical use of Faraday law

    Hello, I have the following question, I am trying to build a home made hot air gun for electronics soldering, my approach was with a modified Microwave oven transformer, multifilar 12mmxmm copper cables, and a 15cm stainless steel tube, the air is pumped from a powerful aquarium air pump. The...
  5. T

    Would a Faraday cage block all types of radar?

    Would a faraday cage block all types of radar?
  6. M

    Dual Faraday Tensor - Levi Civita Problem

    Ok I'm trying to calculate the Dual Faraday Tensor, but I'm having trouble with the notation I think... *F^{ab} = \frac{1}{2}E^{abcd}F_{cd} where E is the levi-civita symbol. I'm correct in that E^(1234) = 1 for (1234,3412,2341,4123) -1 for (4321,3214,2143,1432) 0 otherwise...
  7. S

    Modified Faraday Disc: EMF Calculation

    The EMF for the Faraday disc is calculated as \epsilon = \int_0^R \textbf{v} \times \textbf{B} \cdot d\textbf{l} the integration is between the disc axis (0) and its edge (R is the disc radius). As for uniformly rotating disc \boldmath v = \omega \times r and B-field is orthogonal to the...
  8. G

    Designing a Faraday Generator Suit | Get Answers Here

    Hello everyone, I need help designing a Faraday Generator suit. It's basically a bunch of small Faraday generators (the kind used in flashlights), sewn into the fabric of outer clothing and connecting to batteries to charge them. The problem is that I have no idea what it will take to make...
  9. C

    Can Magnets Induce Electricity Inside a Faraday Cage?

    Hey there, I was wondering whether the following scenario is possible: Say I have a Faraday Cage which contains electricity on the inside, could I use a magnet on the outside to create electricity on a conductor on the inside? If no, are there possible variations to this scenario which...
  10. A

    Solving the Problem of Unwanted Mains Supply Field in a Faraday Box

    Hello, I have constructed a Faraday box with alluminium sheets having holes on them. The problem is that the mains supply field is not canceled within this box. The box is about 50cmx50cm and hosts a number of electrodes and an electrical drive that moves these system of electrodes. I...
  11. A

    Can a Faraday Cage Effectively Shield Against 13.56 MHz RF Interference?

    I'm working on a project that has a 13.56 MHz RF power source. The thing is, the EM waves emitted by this power source cause problems with the diagnostic equipment of the actual experiment (various capacitive and inductive sensors). So, I am planning to build a faraday cage to shield the...
  12. H

    Car Struck by Lightning: Faraday Cage or Skin Effect?

    Most places I've read say it's because the car forms a Faraday cage, but a few say that is incorrect and that it's actually from the skin effect. The notable case of the latter explanation is from the Boston Museum of Science: http://www.mos.org/sln/toe/cage.html This guy, Dr. Davis from the...
  13. L

    Faraday cage problem with RFiD

    I'm working in a tracking solution based on RFiD, that consists on tags without any type of battery or power source. When the antenna generates the signal in the correct frequency, an induction process occur in the tag, generating a response to the antenna (containing the tag's id number)...
  14. R

    Faraday Generator - Theoretical

    Hello. So I need a little bit of help with this. I am trying to 'make' a theoretical generator, that is powered by a wind station. There are so many variables that I either need to make up or find, such as coil thickness, length etc. So I was wondering whether anyone could help me? Can someone...
  15. C

    Tesla Coil Surprises Inside a Faraday Cage

    When this guy gets inside the Faraday cage and they hit it with like 200,000 volts from a Tesla coil , when he is inside the cage he can touch the inside and not get shocked , so basically the charge flows on the outside , is this because the electric field from all around the circle pushes...
  16. N

    Does the lightbulb burn? (Faraday)

    Apologies for the atrocious attempt at a drawing: So my professor said that if you close the switch, the upper lightbulb (n° 2) will go out. How exactly do you know this? Well of course, if you replace the changing magnetic field that is inducing an emf with a battery somewhere close to...
  17. T

    How Can an Electric Field Disturb a Faraday Cage?

    Hi everyone! I was thinking..then I decided to post this thought to ask your opinion about that. We have this capacitor made by different layers, starting from the top we have: electrode, dielectric material (let's assume 10um thick, permittivity k=600), conductive layer (good liquid...
  18. N

    Origin of non-conservative Faraday

    The non-conservative nature of an induced E-field due to a changing magnetic flux has always interested me. In the case of a constant magnetic field and a circuit with a changing surface, the changing magnetic flux can actually be written as a line integral of v x B (*), with v the speed of the...
  19. S

    Electron gun design using faraday cage like setup

    I have designed an electron gun that incorporates a faraday cage setup and I would like anyone's opinion if this setup could actually work. See attachment for image or here is a link to the image of the electron gun http://yfrog.com/j7electrongundesignbj Explanation of image There is a...
  20. P

    Writing the Faraday tensor for a particle in an E field

    Homework Statement A particle of charge q and mass m is traveling in the lab with velocity v in the x direction when it encounters a constant E-field in the y direction. State the non zero components of the Faraday tensor in the rest frame of the lab. The Attempt at a Solution I said...
  21. P

    Invarients from the Faraday tensor

    Hello, a full contraction of the faraday tensor with itself can be shown to be F_{\mu\nu}F^{\nu\mu}=2(E^{2}-c^{2}B^{2}) I have done this by calculating 16 terms in the sum i.e. F11F11 + F12F21, and get this answer, but this is very tedious. Is there a faster way to show this that I...
  22. B

    Faraday Rotation experiment question

    Homework Statement I used a Faraday Rotator to measure the Verdet constant of SF-59 glass at 650 nm wavelength. In this setup, the glass sample was placed inside a solenoid, and a diode laser was aligned to enter the solenoid and go through the sample. The angle of rotation of an analyzer...
  23. K

    Faraday cage experiment - Static current

    Hi everybody. Some expert advice needed here. I am working into an experiment that consists of putting a wave emitter device (a wi-fi router for example) in a faraday cage so those waves don't spread outside the cage (or I get some attenuation at least). I have some questions: - First of...
  24. E

    Kirchhoff's Law Derived from Faraday's Induction - EMROZ

    Please see the attachment. There I have derived Kirchhoff's Voltage law from Faraday's Induction law. Reply me if I have done something wrong and also notify me if this proof has been made somewhere else. Thanking you, EMROZ
  25. J

    Build Faraday Flashlight: Will Generator Work?

    Homework Statement I am trying to build a faraday flashlight and I need to know if this generator would work. Homework Equations I added a rough diagram to help illustrate this...3. The attempt at a solution I have a DIA20 x L10 cylindrical Neodymium magnet moving up and down inside a plastic...
  26. W

    Why negative sighn in faraday law of electromagnetic induction?

    pleasezzzzzz anyone can clear me on this point: why -ve sighn comes in faraday law of electro magnetic induction?what is it sighnificance?if in answer value of induce EMF become -ve than waht will be its direction.
  27. I

    Auto-Compensating Polarization Changes with Mirror/Reflector and Faraday Mirror

    Hi, I read several literatures on quantum cryptography plug and play system. I found out that Faraday mirror was used to compensate polarization fluctuations. Photons are reflected orthogonally by Faraday mirror and their polarization changes will then be autocompensated, provided they follow...
  28. L

    Inverse Faraday Cage: Containing Magnetic Fields?

    Well we can use a Faraday Cage to keep magnetic fields from entering a certain area, but I was wondering if the same method could work for containing magnetic fields. I know we use metal cores to concentrate magnetic fields, but is there a way to actually trap them?
  29. D

    What is the induced current in a moving frame near a changing current wire?

    in the following question i am given an infinite straight wire with a current changing according to i=2t, next to the wire is a conducting square with a side of a=5cm at t=0 the square is at a distance of b=5cm from the wire and the frame is moving away from the frame at v=2m/s, the frame has a...
  30. K

    Solve for Bmax: Quick Faraday Equation with Transformer Parameters

    I have this equation and the following values for a transformer Bmax= (V1)/(4N1fA) V1=10v, i.e. 20v peak-to-peak N1=40 turns f=5000Hz A=76x10-6 m2 When i substitute in the voltage, do i use the 10v, or the peak to peak, or would i have to convert to Vrms
  31. P

    Calculating Induced Current in a Circular Loop Inside a Solenoid

    Homework Statement A long solenoid of radius a , is driven by an alternating current , so that the field inside is sinusoidal: B(t)=B0cos(omega*t)z-hat. A circular loop of wire, of raduis a/2 and resistance R, is placed inside the solenoid and coaxial with it. Find the current induced in the...
  32. R

    Building a Cheap Faraday Cage in Bedroom

    1. Suffer extreme symptoms from Microwave RF emissions cell phones, Wi FI, Cordless computers and RF Routers. 2. The next door neighbour has installed a Uniden DECT that transmits continually 24 hours a day. Our bedroom and the next door neighbours loungeroom is separated by a normal...
  33. A

    Making a mobile van faraday cage

    A real life situation exists where I'm attempting to turn the back of a van into a faraday/rf sheilded cage to transport 2 electromagnetic sensitive beings too properties where there is no microwave tower coverage in the hope they can live fuller longer lives (than are currently expected) in a...
  34. P

    Building Faraday Flashlight Help

    Homework Statement I need to build a faraday flashlight and I have two problems. Homework Equations (1) When I use a 12V DC motor connected in parallel to a capacitor (16V 2200uf) and then to an LED assembly, I can't get the capacitor to charge. (2) If I wanted to use a magnet and coils...
  35. M

    Equation help desperately needed Faraday Equation.

    Hello, What do i substitute the 'd' and 't' for in this equasion: It just didnt say, so i am a bit lost!
  36. JasonGodbout

    Exploring the Faraday Effect: Examining Polarization with Matlab

    Homework Statement I ave a research to do on Faraday effect. I found an explanation were they said that a linearly-polarized beam of light may be considered as the superposition of equal amounts of right- and left-circularly polarized beams. The right- and left-circularly polarized beams or...
  37. J

    Can a Faraday Cage Protect Against EMF Radiation from Neighbors?

    Couple of months ago Deany100 posted a note on microwave radiation which he suspected was his neighbour tracking his movements. I've got a similar problem, a home bathed in emf picked up by a device (15 pounds sterling) that doesn't tell me what the frequency is. Great disbelief from everyone...
  38. K

    Faraday Cage Concept and Building Questions

    I have a few questions and verifying statements regarding the concept as well as practical building of Faraday Cages. 1. A Faraday cage's mesh must have a grid with a spacing less than that of the wavelength that is intended to be stopped. 2. Why is it that foil and mylar also work as...
  39. C

    What is the time period for a rotating coil in a constant magnetic field?

    A circular coil, with radius of 10 cm, and 25 turns, rotates in a constant magnetic field of strength 2.4 T, with the axis of rotation perpendicular to the direction of the magnetic field. If the coil rotates at a frequency of 50 Hz, what is the induced peak voltage? Okay so I know the...
  40. N

    The Faraday disc (unipolar generator) and Lenz' law

    Homework Statement Hi all. I can't seem to understand how to apply Lenz' law to a disc rotating in a magnetic field that is perpendicular to the discs plane (see first page on PDF): http://www.pa.uky.edu/~latimer/phy232s08/lectures/phy232l31_4.pdf I can see that using the right-hand...
  41. K

    Building a Successful Faraday Cage for Cell Phone Signal Cancellation

    Homework Statement For my physics project I decided to make a Faraday cage to cancel out cell phone signal. Homework Equations The Attempt at a Solution For my first attempts at making a successful project I used chicken wire and wire mesh to make a cylindrical cage. Our goal was...
  42. Angelos K

    Why is my Faraday cage not working?

    Dear readers! I wanted to arrange a little demonstration for my relatives with my cellphone inside a Faraday cage. Of course I expected no EM waves to be present inside the cage, which means that my cellphone wouldn't ring when being called. Well, we repeated the experiment several times...
  43. V

    Charges on Faraday ice bucket like conductors

    Hi, I have problems with charge distributions of buckets and other conductors which has a cavity. If there is experiments, photos, detailed examples about this kind of charges then glad to learn the links in net. Suppose have a conductor like Faraday ice bucket. And tied two un-charged...
  44. R

    E and M fields in a faraday cage

    I have a question regarding Faraday Cages... Faraday Cages blocks static electrical fields I read somewhere that static magnetic fields can penetrate the faraday cage when changed slowly. Faster changes in static magnetic fields cannot penetrate a faraday cage, is this true? Also does...
  45. P

    Exploring the Effects of Inserting Current into an Ungrounded Faraday Cage

    Hi! I want to know what will happen if I insert current (moving electrons) into Faraday cage, which is ungrounded? Will still there be no electric field, inside the cage?
  46. P

    Can external current pass through Faraday cage,like thunder?

    Can external current pass through Faraday cage,like thunder? Will be there electrical field, inside the Faraday cage?
  47. K

    Solved: Faraday Cage Problem - No Electric Charge on Man

    [SOLVED] Faraday cage problem A man is standing on a rubber mat which is isolated. You place a Faraday Cage around the mat. (the cage is standing on top of the mat) The man is touching the cage Now when lightning hits will: 1) the cage be loaded with electricity 2) the cage not be loaded...
  48. P

    Will 4 sides FARADAY CAGE work?

    Hello all, I plans to reduce RF strength in my apartment by cover the room with conductive material. - Cover 2 walls which facing the boardcasting tower. - Cover the floor and ceiling. Total 4 sides (since the material is quite expensive) Then I'll grounded them to the apartment...
  49. S

    Electric Field in Faraday Cage: Effects on Shielding

    i heard that a faraday cage is often used in shielding e.g. sensitive electrical equipment. I was just wondering, because, in http://socrates.berkeley.edu/~fajans/Teaching/cartoons/Shielding/TestChargeShielding_files/frame.htm it seems that the electric field is not zero at ALL times. i.e...
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