Basics of Electric and Magnetic Fields

What are electric and magnetic fields?

Electric and magnetic fields (EMFs) are present wherever electricity flows — around appliances and powerlines, and in offices, schools and homes.

  • Electric fields are invisible lines of force created by voltage. Voltage is the electric force that causes current in a conductor, and are shielded by most materials.
  • Magnetic fields are invisible lines of force created by current, movement of electrons in a conductor. They are not shielded by most materials such as lead, soil and concrete. 


  • Electric fields are measured in volts per meter (V/m).
  • Magnetic fields are measured in Gauss(G) or milligauss (mG) or Tesla (T) or microtesla (µT) units.

How are milligauss and microtesla related?

  • 1 microtesla = 10 milligauss
  • 1 Gauss = 1,000 milligauss
  • 1 Tesla = 1,000,000 microtesla

Other EMF Properties

  • Electric and magnetic field strengths diminish with distance.
  • These fields are low energy, extremely low frequency (ELF) fields.
  • They are not to be confused with high energy or ionizing radiation such as x-rays and gamma rays.

Additional Information

National Institute of Environmental Health Sciences*

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