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B Elektrical and kinetic energy

  1. Apr 29, 2016 #1
    I got a question towards kinetic energy and elektrical energy. They always talk about about particle accelerators or devices when talking about transformation of elektrical energy into kinetic energy of elektrons. But do elektrons also have kinetic energy when they are circulating in an elektrical cirquit without any devices? And if elektrical energy is transformed into kinetic energy, because the electrons are moving, there has to be energy consumption right? Thanks in advance
     
  2. jcsd
  3. Apr 29, 2016 #2

    jbriggs444

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    Electrons are very light. In a conductor their average velocity (i.e. their "drift velocity") is very low. Yes, they have kinetic energy, but it is extraordinarily tiny.

    If you apply a voltage across a resistor, thus creating a current, the electrons are moving and do have this tiny amount of kinetic energy. You can think of the electrons as bumping around within the resistor at a high speed as they drift at a low average velocity under the influence of the voltage. Between bumps, the electrons are gaining kinetic energy on average due to the applied voltage. At each bump they lose kinetic energy on average because the resistor is stationary. This heats up the resistor. Yes, it takes a continuous supply of energy to maintain a current through a resistor because the electrical energy is converted to heat energy in this manner.
     
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