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This module beqins the study of electricity. Not only is it true that we see nature's gigantic electrical show in thunderstorm displays with lightning, but the very functioning of our smallest cells depends on the balance of electrically charged ions, and their movement through cell membranes. On a larger scale than cell membranes, water-purification studies with large membranes show promise of "electrically" removing undesired ions or debris from water. The electronic air cleaner is yet another direct application of the material to come: a 7000-V potential difference between a thin wire and flat collecting plates ionizes the air, and the "flying" electrons attach themselves to dust particles, which are then pulled to the collecting plates by strong electrical forces. Since forces that hold atoms together are ultimately electrical, the study of electricity is the study of one of nature's truly grand designs.
Later in your study of physics you will see the design unfold further; charges whose position is constant produce electric fields, charges whose velo~ity is constant produce magnetic fields as well as electric fields, and charges that accelerate produce that special combination of electric and magnetic fields we know as electromagnetic radiation (radio waves, x rays, microwaves, etc.).