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Lorentz force law equation

  1. Jan 2, 2014 #1
    How do we say that F=BIL SINΘ using the SI units?:confused:
    newton(N)= Weber/m2 * ampere*meter.

    please explain as soon as possible.:approve:
  2. jcsd
  3. Jan 2, 2014 #2
    Use magnetic lorentz force on a charged particle equation. And you can prove

    F=BqvsinΘ.(Magnitude only).

    so B= F/qvsinΘ
    So, the unit of B is N/C(ms^(-1))

    multiply s on both numerator and denominator,

    so the unit is Ns/Cm

    But F = BILsinΘ (Force on current carrying wire)

    Unit of RHS is therefore

    Here A is ampere But A=Cs^(-1)

    Substituting, you get the unit as N which is the unit of LHS
    Last edited: Jan 2, 2014
  4. Jan 2, 2014 #3
    A Weber is also energy in joules (stored in field) per ampere. So the amperes and numerator meter cancel and you are left with force (N) = energy (J) / length (m)...which is true since work is force times displacement. You could also break the Joule down into (mass * velocity squared) kg*m^2/s^2. Observe dividing a meter gives you the Newton (mass * acceleration) (kg*m/s^2).
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