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electrika
electrika
Student
College - Freshman

An electron, accelerated before by a potential difference U=300V is moving parallel with a long rectilineal conductor, crossed by a current,I=5A.

 

The distance between electron and conductor is r=4mm. What force is operating on electron?

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Posted by electrika on Wednesday July 1, 2009 at 3:13 AM and tagged with electron, lorentz force, potential difference, rectilineal conductor, science.

Answers:

  1. kjcdb8er
    kjcdb8er Teacher

    eNotes Editor

    The electon accelerated by a potential of U=300 V has qU of kinetic energy.

    So 300q = (1/2)mv^2 ---> the electron is traveling v = 0.10x10^8 m/s (or 3% of the speed of light).

    The magnetic field induced by current in the wire is : B = uI/2PIr. So B = (4PIx10-7 H/m * 5A)/(2PI * 0.004 m) = 250x10-6 Wb/m^2 = 250 uT.

    The force on a charged particle moving through an electrical and magnetic field is: F = q(E + v x B). Since the motion of the electron is parallel to the wire, the cross product reduces to vB. The E field outside of the conductor is zero.

    So, F = -q0.1x10^8 m/s * 250x10-6 T = -2500 N

     

    Sources:
    http://www.enotes.com/physic/q-and-a/particle-with-specif...

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    Posted by kjcdb8er on Wednesday July 1, 2009 at 2:54 PM