Presentation on theme: "Electromagnetism and Energy"— Presentation transcript:
1 Electromagnetism and Energy Causes and effects ofstatic and dynamicelectric & magnetic fieldsMaxwell equations yieldelectromagnetic wavesElectromagnetic energyThermal energy:heating, melting, boiling,Potential energy:electrostatic, gravitationalKinetic energyBernoulli equation
2 Electrodynamics Giancoli Ch.21-29 Physics of Astronomy, winter week 6 Star DateHW: finish CO 3.6, magnitudesOverview of EM & Maxwell’s eqnsMinilecturesDerive EM wave equation and cNext week: write Interim Research Planning ReportBoas Ch.4: partial differentiation (1-6)Week 8: Modern physics + CO Ch.5: Interaction of light and matter
3 Causes and effects of E Gauss: E fields diverge from charges Lorentz: E fields can move chargesF = q E
4 Causes and effects of B Ampere: B fields curl around currents Lorentz: B fields can bend moving chargesF = q v x X = IL x B
5 Changing fields create new fields! Faraday: Changing magnetic flux induces circulating electric fieldGuess what a changing E field induces?
6 Changing E field creates B field! Current piles charge onto capacitorMagnetic field doesn’t stopChanging “displacement current”
8 Maxwell eqns electromagnetic waves Consider waves traveling in the x direction with frequency f= w/2pand wavelength l= 2p/kE(x,t)=E0 sin (kx-wt) andB(x,t)=B0 sin (kx-wt)Do these solve Faraday and Ampere’s laws?