The magnitude of the magnetic field (B) at a distance 'r' from a long, straight wire carrying a current 'I' is given by the formula $B = \frac{\mu_0 I}{2\pi r}$ (in vacuum or air). This formula shows that B is directly proportional to the current I and inversely proportional to the distance r.
A straight conducting wire carries a DC current through it. Which one of the following statements is true regarding the magnetic field around the wire?
Asked in UPSC Geoscientist 2020 · Topic: Electric Current (Ohm's Law, resistance, resistivity, and conductivity)
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Answer: D. The magnetic field decreases with an increase from the wire
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