Module 3 : MAGNETIC FIELD
Lecture 14 : Force on a Current Carrying Conductor
  Example 1 :

Force on a Straight Wire carrying current $I$
If the wire is straight $\hat u_l$is a constant vector. For a uniform magnetic field $\vec B$

\begin{displaymath}\vec F = I (\hat u_l\times\vec B)\int dl = IL(\hat u_l\times\vec B)\end{displaymath}

The wire experiences a sidewise force. The direction of the force is given by Fleming's Left Hand Rule.

Fleming's Left Hand Rule
If one stretches out the forefinger, the middle finger and the thumb of one's left hand so that they are mutually perpendicular to one another, then, if the middle finger points in the direction of current and the forefinger points in the direction of the magnetic field, the thumb will point in the direction of the force.

\includegraphics{fig3.8.eps}

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