Lecture 24 preview apr3 - Lecture 24 EM Waves Today: EM...

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Lecture 24 EM Waves Today: EM waves, (and exam #3) Next Tuesday: More EM waves Next Thursday: Nature of Light Next, next Tuesday: Electric Power and Final Exam thoughts
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Maxwell’s Eqs. in free space away from charge & currents dt d I l d B A d B dt d l d E q A d E E c B exclosed Φ + = = Φ - = = 0 0 0 0 0 0 ε μ dt d I l d B A d B dt d l d E A d E E c B Φ + = = Φ - = = 0 0 0 0 0 0 dt d l d B A d B dt d l d E A d E E B Φ = = Φ - = = ∫ ∫ 0 0 0 0 If then the equations are interchangeable in E and B SURPRISE! = C , the velocity of light…… s m / 10 3 1 8 0 0 × = 0 0 B E = We will see that light waves consist of oscillating, perpendicular E and B fields that perpetually induce each other, propagate at speed c, with E = cB.
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The half-space of uniform, crossed E and B vB E thus dt dx Ba dt dA B Ea dt dA B A dt dB Ea l d E = = = + - = - = ) ( 0 a “curtain” How does Φ B change if B=constant?? Φ - = - = dt d Ea l d E Law s Faraday B 0 : ' x E=0 B=0 The “curtain” is a wavefront that propagates to right in direction of E X B. What’s velocity v???
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This note was uploaded on 04/04/2008 for the course PHYSICS 240 taught by Professor Davewinn during the Spring '08 term at University of Michigan.

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Lecture 24 preview apr3 - Lecture 24 EM Waves Today: EM...

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