what is electromagnetism - Delaware Physics

1 What is electromagnetism ? Introduction in PicturesBranislav K. Nikoli Department of Physics and Astronomy, University of Delaware , 208 Honors: Fundamentals of Physics ~bnikolic/teaching/phys208 208 Honors: What is electromagnetism ? electromagnetism : FundamentalsPHYS 208 Honors: What is electromagnetism ? electromagnetism : ApplicationsPHYS 208 Honors: What is electromagnetism ?Origin of Charged Objects: Elementary Particles, Standard Model, and All ThatPHYS 208 Honors: What is electromagnetism ?Fundamental Forces Between Elementary ParticlesPHYS 208 Honors: What is electromagnetism ?

2 History of Elementary ParticlesPHYS 208 Honors: What is electromagnetism ?Coulomb Force vs. Gravitational Force12 Coulomb1 on 22 on 12014 Coulombq qFFr ==121 on 22 on 12gravitygravitym mFFGr==2electron on proton39electron on proton01104 CoulombelectrongravityelectronprotonFqFG mm = PHYS 208 Honors: What is electromagnetism ?Expressing Force Action Through Fieldonat ( , , )( , , )qx y zFE x y zq=PHYS 208 Honors: What is electromagnetism ?Examples of Gravitational FieldsPHYS 208 Honors: What is electromagnetism ?

3 Electric Field of Point ChargesPHYS 208 Honors: What is electromagnetism ?Where Does Magnetism Come From? Magnetic fields are produced by electric currents, which can be macroscopic currents in wires, or microscopic currents associated with electrons in atomic orbits magnetic field sources are essentially dipolar in nature, having a northand south magnetic pole.(Ga,Mn)AsPHYS 208 Honors: What is electromagnetism ?How strong is Magnetic Force?LorentzFqE=+ v v 1 on 220(2)4electricqFqq Er == qq121 on 22(2)(2)magneticvEFq vBq vc== 03(2)4qv rBr = 301(2)4qErr = r 002(2)(2)(2)v EBv Ec = = q vB 1 on 21 on 22magneticelectricFvcF = 2410for two copperwires PHYS 208 Honors: What is electromagnetism ?

4 Electric vs. Magnetic vs. Electromagnetic Field002 EEvBvcvEBBc =+ = Electric and magnetic fields are not invariant entities themselves, but are aspects of a single entity, the electromagnetic field, which manifests itself differently to different moving observers. PHYS 208 Honors: What is electromagnetism ?Electrodynamics: Electromagnetic Waves