CHAPTER 1 - CURRENT AND POTENTIAL DIFFERENCE

Abstract

Two types of charged particles are involved in the structure of any material—the positively charged nuclei of the atoms and the negatively charged electrons moving around the nuclei. When no current flows in a stationary conductor, the continual orbiting and jostling of these particles lead to no resultant large-scale movement of either positive or negative charge one way or another. If an electric cell is connected in a closed circuit of conductors, the cell tends to drive negative particles one way around the circuit and positive the other. The direction of flow of the positive charge is the direction of the current. In most solid conductors, electric currents consist only of those electrons that are free to drift through the solid, while the positive nuclei, with orbiting electrons, remain localized in the solid structure. Many effects of currents are the same whether because of positive particles drifting in one direction or to negative in the other. When an electric current flows in a wire, a magnetic field is produced in the surrounding space or medium. Evidence of this field is provided by the force exerted on a magnetic compass or on another conductor carrying a current. Such a force can be attributed to the existence of magnetic flux, which is imagined to pass around the current causing the field, and to have the same direction as a compass needle.