  We study a spinor condensate of Rb-87 atoms in F = 1 hyperfine state confined
in an optical dipole trap. Putting initially all atoms in mF = 1 component we
observe a significant transfer of atoms to other, initially empty Zeeman states
exclusively due to dipolar forces. Because of conservation of a total angular
momentum the atoms going to other Zeeman components acquire an orbital angular
momentum and circulate around the center of the trap. This is a realization of
Einstein-de Haas effect in a system of cold gases. We show that the transfer of
atoms via dipolar interaction is possible only when the energies of the initial
and the final sates are equal. This condition can be fulfilled utilizing a
resonant external magnetic field, which tunes energies of involved states via
the linear Zeeman effect. We found that there are many final states of
different spatial density which can be tuned selectively to the initial state.
We show a simple model explaining high selectivity and controllability of weak
dipolar interactions in the condensate of Rb-87 atoms.
