1 / 15

Magnetism and magnetic forces

Magnetism and magnetic forces. Current off. coil. S. N. Molecular magnets aligned randomly. Magnetic field lines (Representing magnetic flux Φ ). Current on. Magnetic field lines (Representing magnetic flux Φ ). coil. N. S. Molecular magnets aligned North to South.

elmo
Download Presentation

Magnetism and magnetic forces

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. Magnetism and magnetic forces

  2. Current off coil S N Molecular magnets aligned randomly

  3. Magnetic field lines (Representing magnetic flux Φ) Current on Magnetic field lines (Representing magnetic flux Φ) coil N S Molecular magnets aligned North to South

  4. Flux density Flux lines Flux density (B) is the amount of flux (Φ) (represented by flux lines) passing perpendicularly through a given area (A) B = Φ ÷ A Φ = B x A

  5. Force on a conductor • When a current flows through a conductor in a magnetic field a force acts on the conductor The direction of the force depends on the direction of the magnetic field and the direction of the current. These directions can be found using Fleming’s Left Hand Rule This is called the motor effect

  6. Direction of current Cross sections of conductor (wire) Current coming out of page(like an arrow coming towards you) Current going into page(like an arrow going away from you)

  7. Force on a conductor Current coming out to page Field Direction N S direction of Force (movement) up

  8. Force on a conductor Field Direction S N Current going in to page Force (movement) Down

  9. Electric motor effect If the conductor is part of a coil with the current going into the coil on the right and out on the left, the coil will spin ( as per an electric motor) S N

  10. Force on a conductor Force = Flux density (B) x current (I) x length of conductor in magnetic field (L) F = B x I x L

  11. EMF induced in a conductor • If a conductor is moved through a magnetic field an EMF (electro-motive- force) is induced in the conductor which causes a current to flow in the direction of the force. • The directions can be found using Fleming’s right hand rule • This is called the generator effect

  12. EMF induced in a conductor Field Direction S N Current (from induced EMF) going into page Movement up through the field

  13. EMF induced in a conductor Field Direction N S EMF induced in a conductor Current (from induced EMF) coming out to page Movement down though field

  14. EMF induced in a conductor The magnitude of the EMF (hence current) induced depends on the rate at which the conductor ‘cuts‘ through the flux lines or ‘the rate of change in flux: E = -dФ/dt The minus sign means that the induced emf opposes the change in flux (Lenz’s Law)

  15. EMF induced in a conductor E = -dФ/dt dФ/dt = dBA/dt(Ф = BA) = dBLxL/dt( L x L = A) E = BLv(v (velocity) = dL/dt B = flux density L = length of conductor in field v = velocity of conductor through field

More Related