What is Electromagnetism? Introduction in Pictures Branislav K. Nikoli ć Department of Physics and Astronomy, University of Delaware, U.S.A.

PHYS 208 Honors: Fundamentals of Physics II http://www.physics.udel.edu/~bnikolic/teaching/phys208/phys208.html Electromagnetism: Fundamentals

PHYS 208 Honors: What is Electromagnetism? Electromagnetism: Applications

PHYS 208 Honors: What is Electromagnetism? Origin of Charged Objects: Elementary Particles, Standard Model, and All That

PHYS 208 Honors: What is Electromagnetism? Fundamental Forces Between Elementary Particles

PHYS 208 Honors: What is Electromagnetism? History of Elementary Particles

PHYS 208 Honors: What is Electromagnetism? Coulomb Force vs. Gravitational Force

1 q1 q 2 m m FCoulomb = F Coulomb = gravity= gravity = 1 2 1 on 2 2 on 1 πε 2 F1 on 2 F 2 on 1 G 2 4 0 r r

F Coulomb q2 1 electron on proton = electron ∼10 39 gravity πε Felectron on proton4 0 Gmelectron m proton

PHYS 208 Honors: What is Electromagnetism? Expressing Force Action Through Field

F E(, x y , z ) = onq at( xyz , , ) q

PHYS 208 Honors: What is Electromagnetism? Examples of Gravitational Fields

PHYS 208 Honors: What is Electromagnetism? Electric Field of Point Charges

PHYS 208 Honors: What is Electromagnetism? Where Does Magnetism Come From?

(Ga,Mn)As

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 north and south magnetic pole.

PHYS 208 Honors: What is Electromagnetism? How strong is “Magnetic” Force? FLorentz = qE + qv× B v v 1 q µ qv× r E(2) = r B(2) = 0 πε 3 π 3 4 0 r 4 r × =ε µ × = v E (2) r B(2)0 0 v E (2) 2 q 1 2 q c vE (2) Fmagnetic = q vB(2) = q v F magnetic 2 1 on 2 2 v  − c 1 on 2 =   ≈10 24 electric electric q F c  for two copper F= q = qE (2) 1 on 2 1 on 2 πε 2 wires 4 0r

PHYS 208 Honors: What is Electromagnetism? Electric vs. Magnetic vs. Electromagnetic Field

 E′ = E + v × B  ≪ ⇒ v0 c  v× E  B′ = B − 0  c 2

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

PHYS 208 Honors: What is Electromagnetism?