CHAPTER 1 BASIC AUTOMOTIVE ELECTRICITY INTRODUCTION Learning  Objective:  Describe  the  basic  principles  of electrical and magnetic theory. Identify the materials, the  devices,  and  the  different  types  of  electrical circuits.  Determine  electrical  measurements  using Ohm’s  law. The  basic  principles  of  automotive  electricity  are the  essential  knowledge  required  by  the  mechanic  to understand  the  operation  of  all-automotive  electrical systems  and  components.  Unless  you  have  a  clear understanding  of  these  fundamental  principles,  you will  find  it  difficult  to  service  the  various  electrical components  and  systems  encountered  in  the  Naval Construction  Force  (NCF).  This  understanding  will enable   you   to   make   sound   decisions   in   the troubleshooting  process  of  all  electrical  systems. BASIC  PRINCIPLES  OF  ELECTRICITY Learning   Objective:   State   the   basic   principles   of electricity, the theory of electricity, and the composition of electricity and matter. All activity that takes place in any type of electrical circuit  depends  on  the  behavior  of  tiny  electrical charges,  called  electrons.  To  understand  the  behavior of  electrons,  we  must  investigate  the  composition  of matter.  The  electron  is  one  of  the  basic  electrical components of all matter. COMPOSITION  OF  MATTER All matter, regardless of state (solids, liquids, and gases), is made up of tiny particles, known as atoms. Atoms combine in small groups of two or more to form molecules; however, when atoms are divided, smaller particles are created. These particles have positive or negative  electrical  charges. There are over 100 different basic materials in the universe.  These  basic  materials  are  called  elements. Iron  is  one  element;  copper,  aluminum,  oxygen, hydrogen, and mercury are examples of elements. The basic particles that make up all the elements, and thus the  entire  universe,  are  called  protons,  electrons,  and neutrons. A proton is the basic particle having a single positive charge; therefore, a group ofprotons produces a positive  electrical  charge.  An  electron  is  the  basic particle  having  a  single  negative  charge;  therefore,  a group of electrons produces a negative electrical charge. A  neutron  is  the  basic  particle  having  no  charge; therefore, a group of neutrons would have no charge. The construction of atoms of the various elements can   be   examined   starting   with   the   simplest   of all—hydrogen. The atom of hydrogen consists of one proton, around which is circling one electron (fig. 1-1). There  is  an  attraction  between  the  two  particles, because   negative   and   positive   electrical   charges always   attract   each   other.   Opposing   the   attraction between  the  two  particles,  and  thus  preventing  the Figure 1-1.—Composition of matter. l-l