Overhead power lines produce a magnetic field. Let us estimate how large this fi

Question

Overhead power lines produce a magnetic field. Let us estimate how large this field is. Suppose a transmission wire is 12 m above the ground. The line operates at 12 kV and provides power of 34 MW to the local area.

Part A:  Estimate the maximum magnetic field produced near the ground underneath such a power line. Remember that for an ac current, electrical values are given as rms, and the magnetic field will be changing.

Bmax = ________________T

Part B: Compare this to the Earth's field of 5.0×105 T.

Explanation / Answer

Here ,

current in the wire is I

Power = V * I

34 *10^6 = 12000 * I

I = 2833.33 A

Now , magnetic field , Bmax = u0*I/(2 * pi*d)

Bmax= 4pi *10^-7 * 2833.33/(2 * pi * 12)

Bmax = 4.723 *10^-5 T

the maximum magnetic field is 4.723 *10^-5 T

part B)

Bmax/Bearth = 4.723 *10^-5/(5 *10^-5)

Bmax/Bearth = 0.945

the ratio Bmax/Bearth is 0.945

Related Questions

Navigate

• Browse (All)
• Browse O
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.