University Physics with Modern Physics (14th Edition)

Published by Pearson
ISBN 10: 0321973615
ISBN 13: 978-0-32197-361-0

Chapter 32 - Electromagnetic Waves - Problems - Exercises - Page 1073: 32.8

Answer

a) $f=6.9\times10^{14}Hz$ b) $B_0=9\times10^{-12}T$. c) $\vec{E}(z,t)=2.70\times10^{-3}\hat{i}\cos\left(2\pi\left(\frac{z}{435\times10^{-9}m}-(6.9\times10^{14}Hz)t\right)\right)$ $\vec{B}(z,t)=9\times10^{-12}\hat{j}\cos\left(2\pi\left(\frac{z}{435\times10^{-9}m}-(6.9\times10^{14}Hz)t\right)\right)$

Work Step by Step

a) $v=f\lambda$, so $f=\frac{v}{\lambda}=\frac{3.0\times10^8m/s}{435\times10^{-9}m}=6.9\times10^{14}Hz$ b) $E_0=cB_0$, so $B_0=\frac{E_0}{c}=\frac{2.70\times10^{-3}V/m}{3.0\times10^8m/s}=9\times10^{-12}T$. c) $\vec{E}(z,t)=\hat{i}E_0\cos(2\pi\left(\frac{z}{\lambda}-ft\right))$ $=2.70\times10^{-3}\hat{i}\cos\left(2\pi\left(\frac{z}{435\times10^{-9}m}-(6.9\times10^{14}Hz)t\right)\right)$ $\vec{B}(z,t)=\hat{j}B_0\cos(2\pi\left(\frac{z}{\lambda}-ft\right))$ $=9\times10^{-12}\hat{j}\cos\left(2\pi\left(\frac{z}{435\times10^{-9}m}-(6.9\times10^{14}Hz)t\right)\right)$
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