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A power cable carries a 100 A current. At what distance from the wire is the magnetic field equal to that of earth, 5.00 x 10^-5 T?

Sagot :

Answer:

  0.4 m

Explanation:

The magnetic field strength is given by the formula ...

  B = (μ₀I)/(2πr)

where I is the current in the wire in amperes, and r is the distance from the wire in meters. The value of μ₀ is 4π×10^-7. We want to find r for B = 5×10^-5. This gives ...

  5×10^-5 = (4π×10^-7)(100)/(2πr)

  r = 2×10^-5/(5×10^-5) = 0.4

At a distance of 0.4 meters from the wire, the magnetic field is equal to that of Earth.