  The role of the parameter `$a$' associated with the Kerr metric which
represents the angular momentum per unit mass of a rotating massive object has
been converted into determining the rotationally induced quadrapole electric
field outside a rotating massive object with external dipole magnetic field. A
comparison of the result with that of the Newtonian case implies that the
parameter `$a$' represents the angular momentum per unit mass of a rotating
hollow object.
