1 / 56

General electric flux definition

qabil
Download Presentation

General electric flux definition

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

    1. General electric flux definition

    2. Magnetic Flux

    3. Gauss’s Law

    4. Gauss’s Law for magnetism

    5. Faraday’s Law

    7. Faraday’s Law

    9. Faraday’s Law of Induction An induced emf is produced by a changing magnetic field. Lenz’s Law – An induced emf is always in a direction that opposes the original change in the flux that caused the emf.

    10. How can we change the flux? Change flux by: Change area Change angle Change field

    14. Faraday’s Law – continued Remember FB is the magnetic flux through the circuit and is found by If the circuit consists of N loops, all of the same area, and if FB is the flux through one loop, an emf is induced in every loop and Faraday’s law becomes

    15. Decaying uniform magnetic field P31.4 Change flux by: Change field Change area Change angle

    16. Applications of Faraday’s Law – Pickup Coil The pickup coil of an electric guitar uses Faraday’s law The coil is placed near the vibrating string and causes a portion of the string to become magnetized When the string vibrates at the same frequency, the magnetized segment produces a changing flux through the coil The induced emf is fed to an amplifier

    18. Linear Generator

    19. Linear Generator with Faraday’s Law

    21. Power moving the bar

    22. Breaking effect if power not added

    24. Rotating Generators and Faraday’s Law

    25. Induced emf in a Rotating Loop The induced emf in the loop is This is sinusoidal, with emax = NABw

    27. Rotating Generators

    28. DC Generators The DC (direct current) generator has essentially the same components as the AC generator The main difference is that the contacts to the rotating loop are made using a split ring called a commutator

    31. Eddy Currents

    32. Self-Inductance When the switch is closed, the current does not immediately reach its maximum value Faraday’s law can be used to describe the effect

    33. Self-induced emf A current in the coil produces a magnetic field directed toward the left (a) If the current increases, the increasing flux creates an induced emf of the polarity shown (b) The polarity of the induced emf reverses if the current decreases (c)

    34. Self Inductance

    35. Inductance of a Solenoid The magnetic flux through each turn is Therefore, the inductance is This shows that L depends on the geometry of the object

    36. Inductance Units

    38. LR Circuits

    39. LR Circuits

    42. Energy in a coil

    43. Energy Density in a coil

    45. Example 32-5: The Coaxial Cable Calculate L for the cable The total flux is Therefore, L is The total energy is

    46. Mutual Inductance

    47. Mutual Inductance example

    48. Induced emf and Electric Fields An electric field is created in the conductor as a result of the changing magnetic flux Even in the absence of a conducting loop, a changing magnetic field will generate an electric field in empty space This induced electric field is nonconservative Unlike the electric field produced by stationary charges The emf for any closed path can be expressed as the line integral of E.ds over the path

    49. General form of Faraday’s Law

    50. E produced by changing B

    51. Maxwell’s Equations

    52. Gauss’s law (electrical): The total electric flux through any closed surface equals the net charge inside that surface divided by eo This relates an electric field to the charge distribution that creates it Gauss’s law (magnetism): The total magnetic flux through any closed surface is zero This says the number of field lines that enter a closed volume must equal the number that leave that volume This implies the magnetic field lines cannot begin or end at any point Isolated magnetic monopoles have not been observed in nature

    53. Faraday’s law of Induction: This describes the creation of an electric field by a changing magnetic flux The law states that the emf, which is the line integral of the electric field around any closed path, equals the rate of change of the magnetic flux through any surface bounded by that path One consequence is the current induced in a conducting loop placed in a time-varying B The Ampere-Maxwell law is a generalization of Ampere’s law It describes the creation of a magnetic field by an electric field and electric currents The line integral of the magnetic field around any closed path is the given sum

    54. The Lorentz Force Law Once the electric and magnetic fields are known at some point in space, the force acting on a particle of charge q can be calculated F = qE + qv x B This relationship is called the Lorentz force law Maxwell’s equations, together with this force law, completely describe all classical electromagnetic interactions

    55. Voltage transformers

    56. Current transformers

    57. Example: transformers

More Related