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A boat travels straight toward the east in a place where Earth’s magnetic field is horizontal, directed due north, and has magnitude 5.0 × 10⁻⁵ N A⁻¹ m⁻¹. The boat has a 2 m tall vertical antenna. If the boat’s speed is 1.50 m s⁻¹, what is the magnitude of the emf induced across the antenna wire?
- 0.75 mV
- 0.50 mV
- 0.15 mV
- 1 mV
Correct answer: 0.15 mV
Solution
With v (east) perpendicular to B (north), v x B points vertically (up), parallel to the vertical antenna. So emf = B v l = 5.0e-5 * 1.50 * 2 = 1.5e-4 V = 0.15 mV.
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