The Structure of Matter

      In the understanding of fundamentals of electricity, the knowledge of the structure of matter plays an important role. The matter which occupies the space may be solid, liquid or gaseous. The molecules and atoms, of which all substances are composed are not at elelemental, but are themselves made up of simpler entities. We know this because we, up to certain extent, are successful in breaking atoms and studying the resulting products. For instance, such particles are obtained by causing ultraviolet light to fall on cold metal surfaces, such particles are spontaneously ejected from the radioactive elements. So these particles are obtained from many different substances under such widely varying conditions. It is believed that such particles are one of the elemental constituents of all matter , called electrons .

       Infact, according to the modern electron theory, atom is composed of the three fundamental particles , which are invisible to bare eyes. These are the neutron, the proton and the electron. The proton is defined as positively charged while the electron is defined as negatively charged. The neutron is uncharged i.e. neutral in nature possessing no charge.

The mass of neutron and proton is same while the electron is very light, almost 1/1840th the mass of the neutron and proton. The following table gives information about these three particles.

                                  

1.1 Introduction

      In practice, the electrical circuits may consist of one more sources of energy and number of electrical parameters, connected in different ways. The different electrical parameters or elements are resistors, capacitors and inductors. The combination of such elements alonghith various source of energy gives rise to complicated electrical circuits,generally referred as networks. The terms circuit and network are used synonymously in the electrical literature. The d.c. circuits consist of only resistances and d.c. sources of energy. And the circuit analysis means to find a current through or voltage acrross any branch of the circuit.

1.Introduction

     The study of the electrical engineering, basiccally involves the analysis of the energy transfer from to another. An electrical machine, deals with the energy transfer either from mechanical form or from electrical to mechanical form. 

     This process is called electromechanical energy conversion.

     An electrical machine which converts mechanical energy into an electrical energy is called an electric generator. While an electrical machine which converts an electrical energy into the mechanical energy is called an electrical motor.

      Such electrical machines may be related to an electrical energy of an alternating type called a.c. machines or may be related to an electrical energy of direct type called d.c. machines.

      The d.c. machines are classified as d.c. generator and d.c. motors. The construction of a d.c. machines basically remains same whether it is a generators or a. motors. But before beginnig the study of the d.c. machines, it is necessary to revise the basic concept of magnetism and electromagnetism.