1 / 24

Magnetism

Magnetism. The shadow of electricity. Magnetic Force. Magnets apply forces to each other. Opposite poles attract, like poles repel. CPS Question. The magnitude of the force between magnetic poles. is the same at all distances. becomes stronger as the poles come closer.

taber
Download Presentation

Magnetism

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 The shadow of electricity

  2. Magnetic Force Magnets apply forces to each other. Opposite poles attract, like poles repel.

  3. CPS Question The magnitude of the force between magnetic poles • is the same at all distances. • becomes stronger as the poles come closer. • becomes weaker as the poles come closer.

  4. Magnetic Field Lines Conventions as with electric field lines. Field lines point from North to South pole. direction is direction of force on a north pole strong field where lines are close together

  5. N B S Group Work • What happens to a dipole magnet in a uniform magnetic field?

  6. Naming the poles N = north-seeking Earth’s north pole is a south pole!

  7. Magnets and Charges

  8. Left Right Up Down In Out Vector Direction Conventions

  9. F = qv  B Magnetic Force on a Charge Source: Griffith, The Physics of Everyday Phenomena Fis directed out of the screen.

  10. Vector Cross Product Operation symbol  Another way to multiply two vectors Product is a vector! • Direction of ABis perpendicular to both A and B

  11. Cross Product Magnitude A  B = ab sin q a A q Maximum for q = 90° Zero for q = 0°, 180° B b

  12. Magnitude Geometrically a A q B b AB = area of parallelogram

  13. If v or B reverse, direction of F reverses Magnetic Force on a Charge • F = 0 unless charge is moving • F = 0 if velocity is  to field • F = maximum if velocity is  to field • F 0 only if charge crosses B field lines • F = qvB sin(q) in general

  14. Group Work What are the units of magnetic field B?

  15. Cross Product Direction Curl right-hand fingers in direction of q Right-hand thumb points in direction of cross-product Not commutative a A q B b AB=–(BA)

  16. F = qv  B Force Direction qv Source: Griffith, The Physics of Everyday Phenomena Right-Hand Rule

  17. paper square Lorenz Force creases:in out qv magnetic current field vectors Origami Right Hand fold over

  18. A. D. B B. E. v C. F. Group Question What is the direction of the force on the object moving with velocity v through magnetic field B? +

  19. B q 2q v v Group Question What is the magnitude of the force on object A compared to the magnitude of the force on object B? A B

  20. B q v Group Work A particle with charge q has a velocity perpendicular to a uniform magnetic field. What will its subsequent path be?

  21. Group Work A current runs through one wire of a pair of side-by-side wires. What is the direction of the resulting magnetic field at the location of the other wire? I ?

  22. Group CPS Question Two parallel wires carrying currents in the same direction • attract each other. • repel each other. • have no effect on each other. Think of their magnetic fields and charge movements!

  23. Force between parallel currents What is the force on this current?I B

  24. Force between parallel currents

More Related