Homework #29

# We just need the magnitude which we can nd using e

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Unformatted text preview: the −y direction, according to the right-hand rule. This means the x component of the magnetic ﬁeld is zero. 013 (part 2 of 3) 10.0 points What is By ? Correct answer: −0.0226667 T. Explanation: Since we know the magnetic ﬁeld points along the −y direction, we know this component is nonzero and we know the sign. We just need the magnitude, which we can ﬁnd using E Explanation: The wave propagates at the speed of light. So we can write distance c= ∆t distance ⇒ ∆t = c 10 m 5 m − (−5 m) = = 8 m/ s 3 × 10 3 × 108 m/s = 3.33333 × 10−8 s . 012 (part 1 of 3) 10.0 points A pulse of radiation propagates with velocity 0, 0, −c m/s where c = 3 × 108 m/s. The electric ﬁeld in the pulse is 6.8 × 106 N/C, 0, 0 N/C. What is the magnetic ﬁeld in the pulse? First give the x component, Bx . Correct answer: 0 T. Explanation: 4 c= . B We have E B= c 6.8 × 106 N/C = 3 × 108 m/s = 0.0226667 T . Taking the sign into account, the y component is −0.0226667 T . 014 (part 3 of 3) 10.0 points What is Bz ? Correct answer: 0 T. Explanation: Following the explanation for part 1, the z component of the magnetic ﬁeld is zero. 015 10.0 points Consider the electromagnetic wave pattern as shown in the ﬁgure below. dedow (kfd235) – Ch24-h1 – turner – (56525) E B What is the direction in which the wave is traveling? 1. undetermined, since the ﬁgure shows a standing wave. 2. from-right-to-left. 3. from-left-to-right. correct Explanation: The direction of traveling is the direction of E × B ; i.e., from-left-to-right. 5...
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