The Science of Electricity

Semiconductors     Definition : The materials, whose electrical conductivity lies between those of conductors and insulators and have negative temperature coefficient of resistance, are known as semiconductors.   Semiconductor Materials : The few examples of semiconductor materials are as under : 1.Carbon (C) 2. Silicon (Si) 3.Germanium (Ge) 4. Selenium (Se) 5.Gallium Arsenide (GaAs) 6.Cadmium Sulphide (CdS). The commonly used semiconductor materials are Germanium and Silicon. These are tetravalent elements i.e. materials having  four valency.   Atomic Structures of Germanium and Silicon : (i) Atomic structure of Germanium and Silicon atoms :  Fig. 1.3 (b) shows the atomic structure of a Germanium atom  in which first, second, third and fourth orbits have 2, 8, 18 and  4 electrons respectively, with the result that the atomic  number for Germanium is 32. Fig. 1.3 (a) shows the atomic structure of a Silicon atom in  which first, second and th

In the previous article Electric Field we had seen that if we gave a charge to any particular particle it experiences a force on it. Now to understand the relationship between force and charge we did an experiment.   Suppose, the charge on a particular particle is q so then the charge particle will experience a force let’s call it as F.  Now if we doubled the charge on the same particle i.e. 2q it will experience double force on it than 1q. So the force on 2q will be 2F. Now we did it again we increased the charge three times i.e. 3q then the force experienced by that charged particle will naturally be 3F acting upon it.  This experiment concludes that more the charge we add on the particle greater will be the force experienced by it . So the force increases as charge on that particle increases.  Therefore, Force is directly proportional to the charge q                              F∝ q                                  -------- (1)   Now we had seen the behav

Introduction :-  If I gave a charge ( either positive or negative) to a particular particle and kept it in a room and what we observed that the charge is moving in a particular direction without being in any contact with anyone or without applying any kind of force. Despite of not applying any kind of force or a contact (by human or by other) to that charge it is moving in a particular direction. But If I took that same charge to a different place or in a different room what we observed? that charge is not moving at all like it was moving in other room instead it is static (not moving).  In some place the charge is moving very rapidly and at some it is very slower; At some places it is moving from left to right at some it  is moving from right to left. But we can't see anything. So what is that force which is driving or moving a charge or applying a force to that charge? What is that unseen thing which is applying force on the charge ? What is that thing in presence

1.1 Introduction: The property of solids that varies most from one solid to the other is the ability to conduct electric current. For example, the resistivity of copper is 1.7 ✕ 10   ^ -8 Ω-m whereas that of quartz is 7.5 ✕ 10 ^ 17 Ω-m. The electron energy bands present in the solids makes it possible to study such a wide variation in resistivity and conductivity. 1.2 Structure of an Atom Any substance, solid, liquid or gaseous is made up of molecules and molecules and molecules are made up of atoms. The atoms contains tiny particles called protons, neutrons and electrons which are called as fundamental particles. Protons have positive charge, electrons have negative charge and neutrons are electrically neutral. The protons, electrons and neutrons of various types of atoms ( atoms of different materials) are same as each other. That means there is no change in their physical properties though they are present in different materials. But the "arrangement" of prot