1 / 23

Electromagnetic Waves: Maxwell's Equations and Propagation Phenomena

Explore the relationship between electric and magnetic fields through Maxwell’s equations and their role in electromagnetic wave propagation. Discover the significance of Maxwell's modifications to Ampère’s Law, leading to the understanding of vacuum field presence. Learn about Hertz's experiments on electromagnetic waves. Dive into the mathematical descriptions of wave behavior and the properties of energy and momentum carried by electromagnetic waves.

arista
Download Presentation

Electromagnetic Waves: Maxwell's Equations and Propagation Phenomena

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. Electromagnetic waves Bringing It All Together

  2. This Week • Today- • No Clickers – sell them back to the bookstore unless you are planning to take my section of the course next semester. Bad idea! • We tie the stuff together and do the candle trick right in front of you. (Remember the video??) • The rest of the week: FINAL EXAMS

  3. My schedule • Tuesday – Not on Campus • Wednesday – Friday • Giving exams • Grading Papers • In foul mood! Stop by if you need to. • Grades will be completed as fast as I can. • Grader has finals this week to, so it may be a slow process.

  4. The Last LectureCovering 5 Additional Chapters • We have been looking at the properties of Electric Fields. • We have been looking at the properties of Magnetic Fields • We looked at a few situations where there was some kind of connection between the two. • We saw that ALL of what we discussed could be explained by one set of equations. • MAXWELL’s Equations

  5. James Clerk Maxwell • 1831 – 1879 • Scottish physicist • Provided a mathematical theory that showed a close relationship between all electric and magnetic phenomena • His equations predict the existence of electromagnetic waves that propagate through space SMART DUDE

  6. Almost Maxwell Bindell Gauss Faraday Ampere E&B Together Problem

  7. Remember the Lowly Capacitor? AC Current=I But there MUST be a magnetic field present around the gap - even if it is small!

  8. Ampère’s Law is used to analyze magnetic fields created by currents: • But this form is valid only if any electric fields present are constant in time • Maxwell modified the equation to include time-varying electric fields • Maxwell’s modification was to add a term

  9. Maxwell Fixed the Problem! • The additional term included a factor called the displacement current, Id • This term was then added to Ampère’s Law • Now sometimes called Ampère-Maxwell Law • This showed that magnetic fields are produced both by conduction currents and by time-varying electric fields

  10. MAXWELL’S EQUATIONS

  11. Vacuum • There ain’t nuttin there. • No Charges • No Currents • Can there be electric or magnetic fields present?? • Maxwell’s equations say YES • And they add some serious requirements to what is there.

  12. Sorry it’s crooked!

  13. Propagation Direction

  14. Back to Maxwell • E & M fields can propagate from a region where there are charges/currents to regions far away where they do not contain these sources. • The fields propagate as WAVES • Shape moves at the speed of the wave. • Because the E field is changing (moving charge example), there will be a B field there as well.

  15. Enter:Heinrich Rudolf Hertz • 1857 – 1894 • German physicist • First to generate and detect electromagnetic waves in a laboratory setting • The most important discoveries were in 1887 • He also showed other wave aspects of light

  16. Hertz Experiment

  17. So far we can assume:

  18. Extended View – Sine Shape

  19. The Magic From M’s 4 • Mathematically these equations describe waves traveling thought space. • E and B are perpendicular to each other and to the direction of propagation. • The velocity of the wave must be

  20. The Velocity is “c: • This must describe light waves …..

  21. It can be shown that the wave carries energy and momentum, Receiver!

  22. How??

  23. FINAL DEMO!

More Related