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Assume we have a conductor that has current flowing and its placed in a magnetic field so that it experiences the Lorentz force, and it gains Kinetic energy due to that force. Would drift velocity change the electron's direction thus the current's total direction changes, therefore, changing the Lorentz force direction applied on the conductor?

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  • $\begingroup$ Are you asking about the Hall effect? This does not change the Lorentz force, it is a consequence of the Lorentz force. $\endgroup$ – honeste_vivere Nov 2 '15 at 17:20
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Yes, sort of. You need a few clarifications.

The Lorentz force due to a magnetic field does not change the kinetic energy of the charges. It changes the momentum (the direction), but not the energy (or the magnitude of the momentum). And as the charges change direction, so too does the direction of the Lorentz force. In the absence of constraints, like the edge of a sample for example, the charges would move in circles.

Drift velocity is associated with an electric field. The magnetic field would not change the average drift velocity of the charge carriers.

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  • $\begingroup$ How would this work? I mean... multiple forces at the same time? F = IL x B and another force? that is calculated with what formula? -- Also, the constraints would reduce the Lorentz force or it would still be the same as initially calculated? $\endgroup$ – Pupil Jun 6 '14 at 5:31
  • $\begingroup$ The Lorentz force is $\vec{F} = q(\vec{E} + \vec{v}\times\vec{B})$ and comprises electric and magnetic forces. Constraints are an additional force. Constraints don't reduce the Lorentz force. The response of the charge carriers is to the the sum of all forces. $\endgroup$ – garyp Jun 6 '14 at 12:15
  • $\begingroup$ Would the change in direction of the electrons, induce another force that would be a resistance to the initial Lorentz force and would cause the decrease in KE? $\endgroup$ – Pupil Jun 6 '14 at 17:39
  • $\begingroup$ Ultimately would the change in direction of that electron induce a resistive force opposing the Lorentz force, or reducing the initially calculated Lorentz force. $\endgroup$ – Pupil Jun 6 '14 at 17:43
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    $\begingroup$ Resistive forces are something else. They really need to be understood in terms of the average velocity of a large number of electrons. They are due to collisions with impurities and phonons. In any event, changing the direction of the electrons induces no new forces. $\endgroup$ – garyp Jun 6 '14 at 19:05

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