What is the Maximum Magnetic Field Under Overhead Power Lines?

Click For Summary
SUMMARY

The discussion focuses on estimating the maximum magnetic field produced by overhead power lines operating at 10 kV (rms) and delivering 44 MW. The relevant formula for calculating the magnetic field (B) is B = μ₀ * I / (2πr), where μ₀ is the permeability of free space, I is the current, and r is the distance from the wire. Participants clarify that the current can be derived from the power and voltage using the equation Power = V²/I, and emphasize the need to consider the vector superposition of currents from both wires when calculating the magnetic field at ground level.

PREREQUISITES
  • Understanding of electromagnetic theory, specifically magnetic fields.
  • Familiarity with the equations for power (Power = V²/I) and magnetic fields (B = μ₀ * I / (2πr)).
  • Knowledge of vector superposition in physics.
  • Basic electrical engineering concepts, including voltage and current relationships.
NEXT STEPS
  • Calculate the current (I) using the power and voltage values provided.
  • Learn about the permeability of free space (μ₀) and its significance in magnetic field calculations.
  • Study vector superposition techniques for analyzing magnetic fields from multiple sources.
  • Explore practical implications of magnetic fields from power lines on human health and safety.
USEFUL FOR

Students in physics or electrical engineering, professionals assessing electromagnetic fields, and anyone interested in the effects of overhead power lines on the environment.

Angie K.
Messages
108
Reaction score
1

Homework Statement



You want to get an idea of the magnitude of magnetic fields produced by overhead power lines. You estimate that the two wires run about 30 m above the ground and about 2.9 m apart. A call to the local power company provides the information that the lines operate at 10 kV (rms) and provide a maximum of 44 MW to the local area. Estimate the maximum magnetic field you might experience walking under these power lines.

Homework Equations



B=mu0*I/2 pi r

The Attempt at a Solution



Would I be able to find the current from the given power and voltage?

Power = V^2/I where V is the voltage (10kV) and I is the unknown current and power is 44 MW

Then using that to find the magnetic field

B=mu0*I/2 pi r

and I'm not sure which value for r to use? Would it be 2.9m/2 because it's the radius I'm interested in?

Thanks in advance!
 
Physics news on Phys.org
Angie K. said:

Homework Statement



You want to get an idea of the magnitude of magnetic fields produced by overhead power lines. You estimate that the two wires run about 30 m above the ground and about 2.9 m apart. A call to the local power company provides the information that the lines operate at 10 kV (rms) and provide a maximum of 44 MW to the local area. Estimate the maximum magnetic field you might experience walking under these power lines.

Homework Equations



B=mu0*I/2 pi r

The Attempt at a Solution



Would I be able to find the current from the given power and voltage?

Power = V^2/I where V is the voltage (10kV) and I is the unknown current and power is 44 MW

The formula for the power is wrong.
Angie K. said:
Then using that to find the magnetic field

B=mu0*I/2 pi r

and I'm not sure which value for r to use? Would it be 2.9m/2 because it's the radius I'm interested in?

Thanks in advance!

You are interested in the magnetic field at your place, on the ground. How far are you from the power lines?
 
Remember you have 2 line with current traveling in opposite direction. There will need to be a vector superposition of the two lines' currents.
 

Similar threads

A particle's momentum in a magnetic field
  • · Replies 3 ·
Replies
3
Views
1K
Power Line Losses: Trivial Problem, Confusing Answer
  • · Replies 9 ·
Replies
9
Views
2K
Does a Bent Wire Affect Induction Calculations?
  • · Replies 7 ·
Replies
7
Views
2K
Electromagnetic effects and Magnetic Fields Questions
  • · Replies 2 ·
Replies
2
Views
2K
Magnetic Field due to Power Lines
  • · Replies 2 ·
Replies
2
Views
9K
Multiple choice question on finding magnetic field
  • · Replies 2 ·
Replies
2
Views
2K
To reduce cost and weight, power transmission lines are made
  • · Replies 6 ·
Replies
6
Views
2K
Torque on a Circular Current Loop under a Misaligned Magnetic Field
  • · Replies 1 ·
Replies
1
Views
1K
Long distance electrical transmission efficiency
  • · Replies 2 ·
Replies
2
Views
2K
High School Magnetic field and generator power output
  • · Replies 5 ·
Replies
5
Views
3K