A length of L copper in the magnetic induction intensity of uniform magnetic field B
1/2BL - W, do not write unit symbols and units are in the formula.
Note: the direction of the magnetic field shown in the diagram must be specified!
If the magnetic field is perpendicular to the surface to the inside, then in accordance with the provisions of the positive direction, V * B is from P to O, and the DL direction is from O to P, so the two reverse vector dot product is 2, the size of the vector product and the 180 degree angle cosine, of course, there will be a negative sign.
