Unformatted text preview: 94. (a) The wave is traveling in the −y direction (see §17-5 for the signiﬁcance of the relative sign between
the spatial and temporal arguments of the wave function).
(b) Figure 34-5 may help in visualizing this. The direction of propagation (along the y axis) is perpendicular to B (presumably along the x axis, since the problem gives Bx and no other component)
and both are perpendicular to E (which determines the axis of polarization). Thus, the wave is
(c) Since the magnetic ﬁeld amplitude is Bm = 4.00 µT, then (by Eq. 34-5) Em = 1199 V/m. Dividing
by 2 yields Erms = 848 V/m. Then, Eq. 34-26 gives
E 2 = 1.91 × 103 W/m .
cµ0 rms (d) Since kc = ω (equivalent to c = f λ), we have
k= 2.00 × 1015
= 6.67 × 106 m−1 .
c Summarizing the information gathered so far, we have (with SI units understood)
Ez = 1199 sin 6.67 × 106 y + 2.00 × 1015 t . (e) and (f) Since λ = 2π/k = 942 nm, we see that this is infrared light. ...
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This note was uploaded on 11/12/2011 for the course PHYS 2001 taught by Professor Sprunger during the Fall '08 term at LSU.
- Fall '08