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Unformatted text preview: Maxwell ’s Equations J. C. Maxwell put the previously known phenomena of electricity and magnetism into mathematical form, and added a new and crucial idea  DISPLACEMENT CURRENT 2 I Ampere ’s Law: Capacitor Consider a charging capacitor : Use Ampere’s Law to calculate the magnetic field just above the top plate 1) Red Amperian Area, I enc = I 2) Green Amperian Area, I = 0 Ampere's law: enc d I μ ! = " B s r r 3 Displacement Current We don’t have current between the capacitor plates but we do have a changing E field. Can we “make” a current out of that? This is called (for historic reasons) the Displacement Current E = Q/ ε A > Q = ε EA = ε Φ E dQ/dt = I d = ε d Φ E /dt 4 Displacement Current: Direction The displacement current flows in the direction of the change in the electric field. If we enclose all of the flux then I d = I I d = ε d Φ E /dt Maxwell ’s Equations Four equations that summarize the creation and interactions of electric and magnetic fields  and predicted that light is an electromagnetic phenomenon....
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 Spring '10
 CatherineBordel
 Current, Magnetism, Magnetic Field, Sine wave, electric charges, J. C. Maxwell

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