1 / 8

Today’s agenda: Magnetic Fields.

Learn the similarities and differences between electric and magnetic fields, calculate magnetic forces on charged particles, understand magnetic flux and Gauss' law, and calculate the motion and trajectory of charged particles in uniform magnetic fields. Explore examples and applications of magnetic fields and forces.

wkenneth
Download Presentation

Today’s agenda: Magnetic Fields.

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. Today’s agenda: Magnetic Fields. You must understand the similarities and differences between electric fields and field lines, and magnetic fields and field lines. Magnetic Force on Moving Charged Particles. You must be able to calculate the magnetic force on moving charged particles. Magnetic Flux and Gauss’ Law for Magnetism. You must be able to calculate magnetic flux and recognize the consequences of Gauss’ Law for Magnetism. Motion of a Charged Particle in a Uniform Magnetic Field. You must be able to calculate the trajectory and energy of a charged particle moving in a uniform magnetic field.

  2. Motion of a charged particle in a uniform magnetic field Example: an electron travels at 2x107 m/s in a plane perpendicular to a 0.01 T magnetic field. Describe its path.

  3. The force on the electron (remember, its charge is -) is always perpendicular to the velocity. If v and B are constant, then F remains constant (in magnitude). - Example: an electron travels at 2x107 m/s in a plane perpendicular to a 0.01 T magnetic field. Describe its path. B                 - F         v                 F         The above paragraph is a description of uniform circular motion. -         v         The electron will move in a circular path with a constant speed and acceleration = v2/r, where r is the radius of the circle.

  4. Motion of a proton in a uniform magnetic field The force is always in the radial direction and has a magnitude qvB. For circular motion, a = v2/r so v    +    Bout FB        r v      + + FB FB        v               Thanks to Dr. Waddill for the use of the picture and following examples. The rotational frequency f is called the cyclotron frequency The period T is Remember: you can do the directions “by hand” and calculate using magnitudes only.

  5. Helical motion in a uniform magnetic field If v and B are perpendicular, a charged particle travels in a circular path. v remains constant but the direction of v constantly changes. B v + v If v has a component parallel to B, then v remains constant, and the charged particle moves in a helical path. There won’t be any test problems on helical motion. *or antiparallel

  6. Apply B-field perpendicular to plane Electrons confined to move in a plane Thanks to Dr. Yew San Hor for this and the next slide.

  7. Apply B-field perpendicular to plane         

  8. Lorentz Force Law If both electric and magnetic fields are present, Applications See your textbook for numerical calculations related the next two slides. If I have time, I will show the mass spectrometer today. The energy calculation in the mass spectrometer example is often useful in homework.

More Related