A system for providing an alternating magnetic field to a polar liquid for changing a property thereof, or for changing a biological response from biological material within the polar liquid, comprising a first at least partially immersible (ALPIM) device comprising: a first signal generator (220, 240, 910) for generating a first alternating electrical current; and, a first transducer (10, 210, 230, 920) for immersing into the polar liquid, comprising: an electrically conductive solenoidal coil (11, 930) for coupling to the first signal generator (220, 240, 910) for providing the alternating magnetic field in response to the first alternating electrical current, the electrically conductive solenoidal coil (11, 930) formed of a plurality of loops each having an interior, the loop interiors forming an interior of the electrically conductive solenoidal coil (11, 930), wherein at least 65% of the interior of the electrically conductive solenoidal coil (11, 930) is not accessible by the polar liquid when the first transducer (10, 210, 230, 920) is immersed in the polar liquid, and two ferromagnetic end pieces (14, 16, 940, 950), one at each end of the electrically conductive solenoidal coil (11, 930) transverse thereto and electrically isolated therefrom, for shaping a portion of the alternating magnetic field external to the electrically conductive solenoidal coil (11, 930), a ferromagnetic core within the interior of the electrically conductive solenoidal coil (11, 930), electrically isolated therefrom, wherein the two ferromagnetic end pieces (14, 16, 940, 950) each have a first cross section size in a direction substantially transverse to the ferromagnetic core, wherein the ferromagnetic core and the electrically conductive solenoidal coil (11, 930) together have a second cross section size in the direction substantially transverse to the ferromagnetic core, and wherein the first cross section size is larger than the second cross section size, characterized in that the two ferromagnetic end pieces (14, 16, 940, 950) are coupled to the ferromagnetic core or integral therewith, and the alternating magnetic field, created by the two ferromagnetic end pieces (14, 16, 940, 960) and penetrating the polar liquid between the ferromagnetic end pieces (14, 16, 940, 960) when the system is operational, has substantially parallel lines of flux. a first signal generator (220, 240, 910) for generating a first alternating electrical current; and, a first transducer (10, 210, 230, 920) for immersing into the polar liquid, comprising: an electrically conductive solenoidal coil (11, 930) for coupling to the first signal generator (220, 240, 910) for providing the alternating magnetic field in response to the first alternating electrical current, the electrically conductive solenoidal coil (11, 930) formed of a plurality of loops each having an interior, the loop interiors forming an interior of the electrically conductive solenoidal coil (11, 930), wherein at least 65% of the interior of the electrically conductive solenoidal coil (11, 930) is not accessible by the polar liquid when the first transducer (10, 210, 230, 920) is immersed in the polar liquid, and two ferromagnetic end pieces (14, 16, 940, 950), one at each end of the electrically conductive solenoidal coil (11, 930) transverse thereto and electrically isolated therefrom, for shaping a portion of the alternating magnetic field external to the electrically conductive solenoidal coil (11, 930), a ferromagnetic core within the interior of the electrically conductive solenoidal coil (11, 930), electrically isolated therefrom, an electrically conductive solenoidal coil (11, 930) for coupling to the first signal generator (220, 240, 910) for providing the alternating magnetic field in response to the first alternating electrical current, the electrically conductive solenoidal coil (11, 930) formed of a plurality of loops each having an interior, the loop interiors forming an interior of the electrically conductive solenoidal coil (11, 930), wherein at least 65% of the interior of the electrically conductive solenoidal coil (11, 930) is not accessible by the polar liquid when the first transducer (10, 210, 230, 920) is immersed in the polar liquid, and two ferromagnetic end pieces (14, 16, 940, 950), one at each end of the electrically conductive solenoidal coil (11, 930) transverse thereto and electrically isolated therefrom, for shaping a portion of the alternating magnetic field external to the electrically conductive solenoidal coil (11, 930), a ferromagnetic core within the interior of the electrically conductive solenoidal coil (11, 930), electrically isolated therefrom, wherein the two ferromagnetic end pieces (14, 16, 940, 950) each have a first cross section size in a direction substantially transverse to the ferromagnetic core, wherein the ferromagnetic core and the electrically conductive solenoidal coil (11, 930) together have a second cross section size in the direction substantially transverse to the ferromagnetic core, and wherein the first cross section size is larger than the second cross section size, characterized in that the two ferromagnetic end pieces (14, 16, 940, 950) are coupled to the ferromagnetic core or integral therewith, and the alternating magnetic field, created by the two ferromagnetic end pieces (14, 16, 940, 960) and penetrating the polar liquid between the ferromagnetic end pieces (14, 16, 940, 960) when the system is operational, has substantially parallel lines of flux.