Doping Silicon To Control It's Conduction Properties.
Section C Case Study - Doping Silicon To Control It's Conduction Properties. Material Properties Silicon is one of the class of materials called SEMICONDUCTORS. So-called because their resistivity lies between good conductors (e.g. metals) and good insulators (e.g. many plastic materials). At room temperature some important resistivities are: Material Resistivity/?m silver .5x10-8 gold 2.1x10-8 copper .6x10-8 silicon 0.6 germanium 0.5 quartz glass x1016 acrylic x1014 At 0K, (i.e. -273.150C), silicon is a perfect insulator. At this temperature, silicon has no free mobile charge carriers because all electrons (negative charge carriers) and holes (positive charge carriers), are bonded to a silicon atom with their covalent bonds. Silicon is in group IV of the Periodic Table which means that it has 4 electrons in the outermost electron orbital-these are called VALENCE electrons as they are responsible for bonding the silicon structure together. In a 2-dimensional representation, this would look like the following: As the above sketch shows, at 0K all electrons are bonded to Si atoms and are not free to carry current. At any temperature above 0K, valence electrons start to break bonds due to the thermal energy they receive. As the valence electron becomes free, a positive hole is also created which can carry current as well as the free electron - under the
Electrical and electronic principles - Application of circuit theory.
GRADE ASSIGNMENT COVER SHEET STUDENT NAME D R HARLOW RANK Fg Off No 8401440B COURSE No/ENTRY 247/1 ASSIGNMENT TITLE ELECTRICAL AND ELECTRONIC PRINCIPLES - APPLICATION OF CIRCUIT THEORY ASSIGNMENT No AB922 VERSION A BTEC UNIT 21759P COMPLETION DATE TUTOR'S NAME MR MIKE SPENCER CERTIFICATE OF ORIGINALITY This assignment report is entirely the original work of the author except for the sources and extracts listed in the bibliography at the back of this document. All direct quotes are enclosed within quotation marks and attributed to the source material, including the page number, directly afterwards. Signature Date ADVANCED ENGINEERING GROUP Royal Air Force Cosford Albrighton WOLVERHAMPTON West Midlands WV7 3EX Tel: (01902) 372393 DFTS: 95561 Ext 7094 BTEC HIGHER NATIONAL CERTIFICATE IN ENGINEERING Course No 1227/5 Fg Off D R Harlow EngTech MIIE RAF ELECTRICAL AND ELECTRONIC PRINCIPLES - APPLICATION OF CIRCUIT THEORY AIMS CONTENTS Page 4 Aim Page 4 Introduction Page 5 Task 1 Page 8 Task 2 Page 10 Task 3 Page 12 Task 4 Page 19 Task 5 Page 23 Task 6 Page 26 Conclusion Page 27 Bibliography AIMS . This laboratory assignment provides an opportunity to: a) Investigate circuit theory b) Design and test symmetrical attenuators c) Analyze complex waves INTRODUCTION 2. The interconnection of components is the essence of an
An Experiment To Find Out How Different Speeds of Stirring a Sugar Cube Help It To Dissolve the Quickest?
AN EXPERIMENT TO FIND OUT HOW DIFFERENT SPEEDS OF STIRRING A SUGAR CUBE HELP IT TO DISSOLVE THE QUICKEST? Introduction If you stir sugar that is in water, it seems to disappear. But the object is still in the water, because if you were to drink it you can still taste the sweetness of the sugar in it. Like in a cup of tea for example. You can explain why this happens by using The Kinetic Theory. The Kinetic Theory The Kinetic theory is the theory that matter is made up of loads of tiny little particles that always move around. This is because all types of matter are made up of little invisible particles which are atoms, molecules and ions. Because all particles move around all the time it means they have to move, but if you freeze the molecules they slow down and if you heat them up they move faster. Heavier particles will move slower than lighter particles in different heats. When a solid dissolves it looks like it has disappeared because its particles get spread in between the water particles. Prediction I predict that the sugar cube will dissolve because there will be movement and the faster the particles move the faster the sugar cubes will dissolve because there is more movement. Diagram Apparatus Magnetic stirrer, sugar cube, beaker, stopwatch, scales Planning I am going to use a magnetic stirrer to stir the sugar cubes in the water for me. I am going to
A Report of My Visit To Alcatel
A Report of my visit to Alcatel Background Alcatel is a large communication company that specialises in fibre optic communication. The main part of their job is to lay cables across the Atlantic Ocean to the Americas. The reason that they only (for the most part) go across to the Americas is the fact that the Asians competitors own the other side of the world and Alcatel find it hard to get to lay cables over that side of the world. As a world leader in the high-speed access and optical transport market, Alcatel is a major player in the area of telecommunications and the Internet. With its expertise in communications systems, it's line of products and services as well as its strong global presence. Identification of Purpose of Physics The two aspect of physics that I saw in the process of my visit that were very important to the running of the company where. 1 lasers. These are fundamental to the running of the organisation. This is how the signal is transmitted down the fibre optic cable. Also another area of physics that is closely related to the laser is total internal reflection (TIR). This is where the laser is fired down the optical tube and is bounced along its length. This will be discussed later. The reason they use lasers is because laser are light that is of a very small and consistent wavelength. Also they are always in phase and move in parallel lines.
Rutherfords Quark theory.
Rutherford In 1911, the British physicist Ernest Rutherford presented his theory of atomic structure. Rutherford, a former student of Thomson's, declared that nearly all the mass of an atom is concentrated in a tiny nucleus, and that the nucleus is surrounded by electrons travelling at tremendous speeds through the atom's outer regions. Rutherford based his theory on the results of experiments in which he bombarded thin sheets of gold with alpha particles. Most of the particles passed through the sheets, which showed that the gold atoms must consist chiefly of empty space. But some particles bounced back as if they had hit something solid. Rutherford concluded that these particles had been reflected by a strong force from the tiny but heavy nucleus of an atom. Rutherford's theory did not explain the arrangement of electrons in atoms. In 1913, however, a description of the electron structure was proposed by Niels Bohr, a Danish physicist who had worked with Rutherford. Bohr suggested that electrons could travel only in a certain set of orbits around the nucleus. Bohr's original, crude picture of the atom was inadequate, but many of the ideas behind it proved correct. In 1924, the French physicist Louis de Broglie proposed that electrons have some properties of waves. By 1928, a correct description of the arrangement of electrons had been obtained with the help
Pressure distribution on an ellipto-zhukovsky aerofoil.
CITY UNIVERSITY DEPARTMENT OF MECHANICAL ENGINEERING AND AERONAUTICS PART II ENGINEERING LABORATORY AERODYNAMICS PRESSURE DISTRIBUTION ON AN ELLIPTO-ZHUKOVSKY AEROFOIL By Amardeep Singh Sanghera Dr Neve ABSTRACT The pressure distribution around an Ellipto Zhukovsky aerofoil with a chord of 254 mm at a range of angles of attack (-4?, 7? and 15?) was determined and pressure contributions to lift were evaluated in a T3 wind tunnel at City University. This was carried out at a chord Reynolds number of 3.9 x 105. Graphs for lift and pitching moment coefficients were plotted against angles of attack. A graph for Cm and Cl was also plotted from which the aerodynamic centre was determined to be 23.7%. The value of lift curve slope was determined to be 4.4759. Hence the value of k (the ratio of the actual lift curve slope to the theoretical one) for this aerofoil was determined to be 0.917. The value of Cmo was also found to be 0.0172. Specimen calculations for 15 degrees angle of attack can be found in the appendix section. LIST OF SYMBOLS Cp Pressure Coefficient Cpu Pressure Coefficient of upper surface Cpl Pressure Coefficient of lower surface Cl Lift Coefficient Cm Moment Coefficient x/c Position of pressure tapping on aerofoil divided by chord length Px Pressure at tapping x (Pa) Patm Atmospheric Pressure (Pa) ? Density of air (kg/m3) µ Dynamic
Conservation of Angular Momentum
Lab #7 Marbles and Siding - Rotational Energy Lauren Anter Minela Gaconovich Jayne Kerner Addison Nordin Dan Popko Joe Rockwell Dani Rosen GE182 - Barnett April 2, 2009 Lab Activities - Phase 1: . What do you think will happen when you allow a ball to roll down the ramp? Will the ball reach the same height on the other side? Make a prediction first, marking your prediction with masking tape on the ramp. Observe. Record what happens below. 2. Was your prediction correct? Why do you think your prediction was right or wrong? We predicted that the ball would reach a point slightly higher than the peak height observed, so we were just about correct. Our prediction was pretty close because we correctly anticipated the amount of energy the ball would have to carry the ball the distance it traveled. Lab Activities - Phase 2: . Before allowing the ball to roll down the ramp predict what you think you will happen? Specifically, what will happen to the stationary ball and what will happen to the rolling ball after the collision? 2. Describe in 3-4 sentences what you observed. Feel free to use diagrams or pictures to illustrate what you observed. Ball 1 was released and traveled down the ramp to hit the stationary ball (Ball 2) placed in the middle of the ramp. After the collision: Ball 1 ceased moving forward briefly but continued to spin, then continued up the
Sedimentation and Fluidisation
Sedimentation and Fluidisation Background: Motion of individual particles in fluids Flow through porous (particulate) media e.g. Galileo numbers, Kozeny's and Ergun's equations. Settling behaviour of concentrated suspensions of fine particles under gravity Observed behaviour in relation to concentration (C) A Clear A Type (a) behaviour Liquid usual if xmax/xmin < 6 c = k c ? k B C C sediment D D (a) (b) 'monodisperse' 'polydisperse' In (a) the boundary between A and B descends down the column until meets C. Modification of settling rates at high C. * Effective density and viscosity increased as large particles settle in a suspension of smaller ones. * Upward velocity of displaced fluid. * Velocity gradients close to particles are increased * Small particles may be drawn in the wake of those larger. * Aggregation rates are promoted at high C. Settling velocities at volume concentrations above infinite dilution Prediction of settling velocities:- ) Use properties of the suspension (?c, ?c) not the (liquid) medium, and use a constant K`` (in place of 1/18) K``x2(?s ? ?c)g uc = ????? [1] µc The effective buoyancy force is readily calculated from suspension voidage (e). ?s ? ?c = ?s ?{?s(1? e) + ?e} = e(?s ? ?) [2] µc is then obtained by experiment or estimated from the Einstein relation using the
Methods Of Particle Size Analysis
2. Methods Of Particle Size Analysis (Some of these are briefly reviewed in Coulson and Richardson 1993) Screening Electronic particle counting (Elzone, Coulter Counter) Sedimentation Optical Methods (i) Microscopy (ii) Laser Diffraction (iii) Dynamic laser light scattering Screening Particles are placed on a screen possessing uniform apertures of given dimensions. Particles capable of passing through the apertures require the opportunity to do so. This is provided by agitation of the load bearing screen for a given period. Particles which pass through this screen can be passed through to a nest of screens of decreasing aperture. The mass retained by each screen is then gravimetrically determined. Screening efficiency is affected by ) Sample load. 2) Particle hardness (in comparison with that of the material of the screen). 3) Duration and intensity of agitation. 4) Presence of large particles which prevent access to screen apertures. Screens are available in a variety of standard sizes and are generally used for material >50?m. Screens of smaller aperture are available but these are often mechanically weak or provide a low proportion of surface as apertures. Such systems are often described as membranes. Classification and separation of many biological particles are performed using membranes. This technology is presented in
The MOSFET - Metal-Oxide-Semiconductor-Field-Effect Transistor
THE MOSFET: Metal-Oxide-Semiconductor-Field-Effect Transistor Introduction: Since the first design by William Shockley, Walter Brattain and John Bardeen in 1947, the transistor has been, and remains, one of the most widely used electrical devices. The transistor is composed of 3 sections or layers of semiconductor material, two p-type materials and one n-type material or 2 n-type materials and 1 p-type material, which can amplify, open, or close a circuit. There are 3 main types of transistors: Bipolar Junction Transistors (BJT's), Field Effect Transistors (FET's) and Insulated Gate Bipolar Transistors (IGBT's). The Junction Field Effect Transistor (JFET), and the Metal-Oxide-Semiconductor-Field-Effect Transistor, or MOSFET are types of Field Effect Transistors. (Boylestad, Nashelsky 115, 219). History: It was 1926 when Dr. Julius Edgar Lilenfied received the patent for his "Method and Apparatus for Controlling Electric Currents" (Maxfield & Montrose), the first transistor-like aparatus. Although the theory behind the device was not yet understood, semiconductor materials were recognized as potential replacements for the established vacuum tube technology which was used for switching and amplification. In the 1940's Bell Laboratories in the United States began research into semiconductors, and in 1947 Shockley, Brattain and Bardeen created the first "point-contact