q04sol - SOLUTIONS Quiz Number 4 PHYSICS 109 Please BOX...

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SOLUTIONS Quiz Number 4 PHYSICS 109 October 12, 2001 Please BOX your answers. c = 3 × 10 8 m / s 1 / 4 π² 0 = 9 × 10 9 m / F μ 0 = 4 π × 10 - 7 N / A 2 . 1. The electric feld o± an electromagnetic wave propagating in the x direction is E = E 0 k sin( kx - ωt ), where E 0 = 3V / m and k = 20 π rad / m. (a) Give an expression ±or the magnetic feld o± this wave. Be sure your expression specifes the direction o± the magnetic feld and gives a numerical value ±or the strength o± the feld. (3 points) E × B must point in the direction of propagation, the x direction. This means B points in the negative y direction. Also, B 0 = E 0 /c . So B = - B 0 j sin( kx - ωt ) with B 0 = E 0 /c = 10 - 8 T . (b) What is the wavelength o± this wave? (1 point) λ = 2 π/k = 0 . 1m . (c) What is the ±requency (Hz) o± this wave? (1 point) c = c/λ = 3GHz . Also ω = 6 π × 10 9 rad /s . (d) What is the average intensity o± this wave? (2 points) h S i = E 0 B 0 / 2 μ 0 = 0 . 012W / m 2 . Rewrite and sign the Honor Pledge:
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q04sol - SOLUTIONS Quiz Number 4 PHYSICS 109 Please BOX...

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