1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Why does DC current not generate EMR?

  1. Apr 22, 2012 #1
    During current flow , electrons are certainly being accelerated and decelerated betweeen two successive collisions with the metal lattice. Since accelerated charge generates EM waves , why doesnt a DC current emit EMR?
  2. jcsd
  3. Apr 22, 2012 #2
    heat is a form of magnetic radiation

    Pass DC voltage thru a wire and heat is the byproduct
  4. Apr 22, 2012 #3
    The drift speed of electrons is incredibly slow compared to the random motions of the electrons. The drift speed is less than a millimeter per second, compared to hundreds of meters per second, for the so the drift speed will make no measurable contribution to the accelerations of the electrons.

    The accelerations of electrons will always cause electromagnetic radiation, and this depends only on the temperature and not on the the presence of current. Until the material becomes so hot it starts to glow, the radiation will be infrared radiation.

    Of course, the current can heat up the material, that will then radiate more infrared.
  5. Apr 23, 2012 #4


    User Avatar
    Staff Emeritus
    Science Advisor

    Heat is not a form of EM radiation. It is the random motion of particles in a material. EM radiation can be converted to heat upon being absorbed though.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook