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Unformatted text preview: 3. (a) The magnitude of the magnetic field due to the current in the wire, at a point a distance r from the wire, is given by µi B= 0 . 2 πr With r = 20 ft = 6.10 m, we have c4π × 10 B= hb 2 π b6.10 mg
−7 T ⋅ m A 100 A g = 3.3 × 10 −6 T = 3.3 µT. (b) This is about one-sixth the magnitude of the Earth’s field. It will affect the compass reading. ...
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