JVC-Janta Vedic College
Chemistry zoology botany
IITK-Indian Institute of Technology Kanpur
This presentation gives an overview of Transcription, Translation and recombinant DNA Technology. The idea for recombinant DNA was first proposed by Peter Lobban, a graduate student of Prof. Dale Kaiser in the Biochemistry Department at Stanford University Medical School.[20] The first publications describing the successful production and intracellular replication of recombinant DNA appeared in 1972 and 1973. Recombinant DNA is widely used in biotechnology, medicine and research. Today, recombinant proteins and other products that result from the use of rDNA technology are found in essentially every western pharmacy, doctor's or veterinarian's office, medical testing laboratory, and biological research laboratory. This presentation starts with the description of various macro molecules, namely Protein, Nucleic Acids and etc, and explain their differneces. <a rel="nofollow" href="http://www-class.unl.edu/biochem/gp2/m_biology/animation/gene/gene_a2.html">Click this line, there is a good presntation over the Transcription is presented in a very attratcive way. </a>
BEC-Balaji Engineering College
When you go through this lecture about Fundelmentals Of Bio Technology, there is a fine need for high concentration due to the high importance of this topic and the level of understanding that you require to get the subject precisely. The subject is very important for all branches of engineering since it is quite closely related to a number of other syllabus topics. A document has been attached that is complete in all means for the help of students.
BEC-Balaji Engineering College
In this lecture, we have explained the Fundelmentals Of BioTechnology and the various aspects of it including the challenges faced and the procedural analysis of it. The topic covers a lot of marks in the syllabus and also is very essential for some other topics as well hence this is important that a student understand it correctly. By downloading the document attached with this lecture you can start learning this topic from the scratch.
SMU-Sikkim Manipal University
This lecture is a technical terminology specific for the Introduction to Biotechnology which is a preliminary topic when you start with the subject. It is very important to get every detail about this topic correctly since this works as the backbone for many of the additional topics in the overall syllabus. To cover the entire topic in just one book and to make it easier to understand a document has been attached for the convenience of students.
SMU-Sikkim Manipal University
Bio Process Principle is considered as the basic knowledge topic in the entire engineering and to properly understand the complete subject it is very much recommended that you go through the depths of this topic first. One cannot simply skip for the higher order topics of discipline unless they know the working mechanism of such an important topic. The attached document will help you in understanding the lecture and the practical knowledge required for this field.
BEC-Bapatla Engineering College
You might have seen network diagrams with a puffy cloud representing the behind-the-scenes components. The cloud conveys the notion that you don’t really need to know the location or number of servers delivering the service. Your experience is that you request a service
BU-Bangalore University
Genetic Engineering is the paper of M.Sc., 3rd Semester in Bangalore university.This paper is of 80 marks and time allotted here is 3 hours. This Paper consists of 3 sections. Section 1 has 7 questions, out of which 5 are to be answered. This section has short notes questions. The Section B has 6 questions. Out of which only 4 is to be answered. The question of this section is of 5 marks each. The final section has long descriptive type questions. There are 5 questions of 15 marks each, out of which candidates require answering any 3.
BIT-Birla Institute of Technology Mesra
Biomolecular Modeling (BIO C417) is the 1st Sem. subject in Birla Institute of Technology and Science, Pilani.The paper is of 2 hours where each question is compulsory and has 70 marks for it. The second part has 30 marks and 1 hours is given to solve this section..
AIIMS-All India Institute of Medical Sciences
<b style="font-family: Arial, Helvetica, sans-serif; font-size: 12px; color: rgb(0, 0, 0); background-color: rgb(255, 255, 255); "><font face="Arial, Helvetica, sans-serif" size="3">Definitions</font></b> <p style="color: rgb(0, 0, 0); font-family: Arial, Helvetica, sans-serif; font-size: 12px; background-color: rgb(255, 255, 255); "> <font face="Arial, Helvetica, sans-serif" size="3"><b style="font-size: 9pt; ">Work</b> can be defined as transfer of energy. In physics we say that work is done on an object when you transfer energy to that object. If one object transfers (gives) energy to a second object, then the first object does work on the second object.</font></p> <p style="color: rgb(0, 0, 0); font-family: Arial, Helvetica, sans-serif; font-size: 12px; background-color: rgb(255, 255, 255); "> <font face="Arial, Helvetica, sans-serif" size="3">Work is the application of a force over a distance. Lifting a weight from the ground and putting it on a shelf is a good example of work. The force is equal to the weight of the object, and the distance is equal to the height of the shelf (W= Fxd).</font></p> <p style="color: rgb(0, 0, 0); font-family: Arial, Helvetica, sans-serif; font-size: 12px; background-color: rgb(255, 255, 255); "> <font face="Arial, Helvetica, sans-serif" size="3"><u>Work-Energy Principle</u> --The change in the kinetic energy of an object is equal to the net work done on the object.</font></p> <p style="color: rgb(0, 0, 0); font-family: Arial, Helvetica, sans-serif; font-size: 12px; background-color: rgb(255, 255, 255); "> <font face="Arial, Helvetica, sans-serif" size="3"><b style="font-size: 9pt; ">Energy</b> can be defined as the capacity for doing work. The simplest case of mechanical work is when an object is standing still and we force it to move. The energy of a moving object is called kinetic energy. For an object of mass m, moving with velocity of magnitude v, this energy can be calculated from the formula E= 1/2 mv^2.</font></p> <p style="color: rgb(0, 0, 0); font-family: Arial, Helvetica, sans-serif; font-size: 12px; background-color: rgb(255, 255, 255); "> <font face="Arial, Helvetica, sans-serif" size="3"><b style="font-size: 9pt; ">Types of Energy</b></font></p> <p style="color: rgb(0, 0, 0); font-family: Arial, Helvetica, sans-serif; font-size: 12px; background-color: rgb(255, 255, 255); "> <font face="Arial, Helvetica, sans-serif" size="3">There are two types of energy in many forms:</font></p> <p style="color: rgb(0, 0, 0); font-family: Arial, Helvetica, sans-serif; font-size: 12px; background-color: rgb(255, 255, 255); "> <font face="Arial, Helvetica, sans-serif" size="3"><u>Kinetic Energy </u>= Energy of Motion</font></p> <p style="color: rgb(0, 0, 0); font-family: Arial, Helvetica, sans-serif; font-size: 12px; background-color: rgb(255, 255, 255); "> <font face="Arial, Helvetica, sans-serif" size="3"><u>Potential Energy</u> = Stored Energy</font></p> <p style="color: rgb(0, 0, 0); font-family: Arial, Helvetica, sans-serif; font-size: 12px; background-color: rgb(255, 255, 255); "> <b style="font-size: 9pt; "><font face="Arial, Helvetica, sans-serif" size="3">Forms of Energy</font></b></p> <p style="color: rgb(0, 0, 0); font-family: Arial, Helvetica, sans-serif; font-size: 12px; background-color: rgb(255, 255, 255); "> <font face="Arial, Helvetica, sans-serif" size="3">Solar Radiation -- Infrared Heat, Radio Waves, Gamma Rays, Microwaves, Ultraviolet Light</font></p> <p style="color: rgb(0, 0, 0); font-family: Arial, Helvetica, sans-serif; font-size: 12px; background-color: rgb(255, 255, 255); "> <font face="Arial, Helvetica, sans-serif" size="3">Atomic/Nuclear Energy -energy released in nuclear reactions. When a neutron splits an atom's nucleus into smaller pieces it is called fission. When two nuclei are joined together under millions of degrees of heat it is called fusion</font></p> <p style="color: rgb(0, 0, 0); font-family: Arial, Helvetica, sans-serif; font-size: 12px; background-color: rgb(255, 255, 255); "> <font face="Arial, Helvetica, sans-serif" size="3">Electrical Energy --The generation or use of electric power over a period of time expressed in kilowatt-hours (kWh), megawatt-hours (NM) or gigawatt-hours (GWh).</font></p> <p style="color: rgb(0, 0, 0); font-family: Arial, Helvetica, sans-serif; font-size: 12px; background-color: rgb(255, 255, 255); "> <font face="Arial, Helvetica, sans-serif" size="3">Chemical Energy --Chemical energy is a form of potential energy related to the breaking and forming of chemical bonds. It is stored in food, fuels and batteries, and is released as other forms of energy during chemical reactions.</font></p> <p style="color: rgb(0, 0, 0); font-family: Arial, Helvetica, sans-serif; font-size: 12px; background-color: rgb(255, 255, 255); "> <font face="Arial, Helvetica, sans-serif" size="3">Mechanical Energy -- Energy of the moving parts of a machine. Also refers to movements in humans</font></p> <p style="color: rgb(0, 0, 0); font-family: Arial, Helvetica, sans-serif; font-size: 12px; background-color: rgb(255, 255, 255); "> <font face="Arial, Helvetica, sans-serif" size="3">Heat Energy -- a form of energy that is transferred by a difference in temperature</font></p> <p style="color: rgb(0, 0, 0); font-family: Arial, Helvetica, sans-serif; font-size: 12px; background-color: rgb(255, 255, 255); "> <font face="Arial, Helvetica, sans-serif" size="3"><b style="font-size: 9pt; ">What is Power</b></font></p> <p style="color: rgb(0, 0, 0); font-family: Arial, Helvetica, sans-serif; font-size: 12px; background-color: rgb(255, 255, 255); "> <font face="Arial, Helvetica, sans-serif" size="3">Power is the work done in a unit of time. In other words, power is a measure of how quickly work can be done</font><font face="Arial, Helvetica, sans-serif" size="3">. </font><font face="Arial, Helvetica, sans-serif" size="3">The unit of power is the Watt = 1 Joule/ 1 second.</font></p> <p style="color: rgb(0, 0, 0); font-family: Arial, Helvetica, sans-serif; font-size: 12px; background-color: rgb(255, 255, 255); "> <font face="Arial, Helvetica, sans-serif" size="3">One common unit of energy is the kilowatt-hour (kWh). If we are using one kW of power, a kWh of energy will last one hour.</font></p> <p style="color: rgb(0, 0, 0); font-family: Arial, Helvetica, sans-serif; font-size: 12px; background-color: rgb(255, 255, 255); "> <font face="Arial, Helvetica, sans-serif" size="3"><b style="font-size: 9pt; ">Calculating Work, Energy and Power</b></font></p> <p style="color: rgb(0, 0, 0); font-family: Arial, Helvetica, sans-serif; font-size: 12px; background-color: rgb(255, 255, 255); "> <font face="Arial, Helvetica, sans-serif" size="3">WORK = </font><font face="Arial, Helvetica, sans-serif" size="3">W=Fd</font></p> <p style="color: rgb(0, 0, 0); font-family: Arial, Helvetica, sans-serif; font-size: 12px; background-color: rgb(255, 255, 255); "> <font face="Arial, Helvetica, sans-serif" size="3">Because energy is the capacity to do work , we measure energy and work in the same units (N*m or joules).</font></p> <p style="color: rgb(0, 0, 0); font-family: Arial, Helvetica, sans-serif; font-size: 12px; background-color: rgb(255, 255, 255); "> <font face="Arial, Helvetica, sans-serif" size="3">POWER (P) is the rate of energy generation (or absorption) over time:</font><font face="Arial, Helvetica, sans-serif" size="3">P = E/t</font></p> <p style="color: rgb(0, 0, 0); font-family: Arial, Helvetica, sans-serif; font-size: 12px; background-color: rgb(255, 255, 255); "> <font face="Arial, Helvetica, sans-serif" size="3">Power's SI unit of measurement is the Watt, representing the generation or absorption of energy at the rate of 1 Joule/sec. Power's unit of measurement in the English system is the horsepower, which is equivalent to 735.7 Watts.</font></p> <div> </div>
AIIMS-All India Institute of Medical Sciences
<h1 style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; "> <a name="Heading1">30. THE MAGNETIC FORCE AND FIELD.</a></h1> <h2 style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; "> <a name="Heading2">30.1. The magnetic force</a></h2> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> Up to now we have only considered the electrostatic forces acting on charges at rest. When the charges are in motion, an extra force acts on them. This extra force is called the <b><u>magnetic force</u></b>. The magnetic force between two charges q<sub>1</sub> and q<sub>2</sub>, moving with velocities v<sub>1</sub> and v<sub>2</sub>, is equal to</center> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3001.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.1)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> where u<sub>0</sub> is called the <b><u>permeability constant</u></b> which is equal to 4[pi] x 10<sup>-7</sup> Ns<sup>2</sup>/C<sup>2</sup>, and r is the distance between the two charges (see Figure 30.1). The ratio R of the magnetic force and the electric force is equal to</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3002.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.2)</span> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3003.gif" /></center> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <b>Figure 30.1. Relevant vectors for definition of magnetic force.</b><br /> </center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">Substituting the numerical values of [epsilon]</span><sub style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; ">0</sub><span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> and u</span><sub style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; ">0</sub><span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> into eq.(30.2), the ratio R can be rewritten as</span> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3004.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.3)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> where c is the velocity of light in vacuum (c = 3 x 10<sup>8</sup> m/s). Clearly, the magnetic force is small compared with the electric force unless the speed of the particles is high (a significant fraction of the velocity of light).</p> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> A magnetic field B can be associated with the magnetic force. The magnetic field at some point in the vicinity of a moving charge can be determined by placing a test charge at that point and moving it with some velocity v. The test charge will experience, besides the electric force, a magnetic force F<sub>mag</sub>. Per definition, the magnetic field B is related to the magnetic force F<sub>mag</sub> via</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3005.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.4)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> A measurement of the magnetic force acting on the test charge for various directions of v can be used to determine the magnetic field B. The magnetic force is always perpendicular to the velocity vector and the direction of the magnetic field. The unit of magnetic field strength is the <b><u>Tesla (T)</u></b>. Comparing eq.(30.1) and eq.(30.4) we can determine the magnetic field generated by a point charge q<sub>2</sub> moving with a velocity v<sub>2</sub>:</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3006.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.5)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> Similar to electric field lines we can graphically represent the magnetic field by field lines. The density of field lines indicates the strength of the magnetic field. The tangent of the field lines indicates the direction of the magnetic field. The magnetic field lines form closed loops, that is they do not begin or end anywhere in the way that the electric field lines begin and end on positive and negative charges. This immediately implies that the magnetic flux through an arbitrary closed surface is equal to zero:</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3007.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.6)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> The principle of superposition is also valid for the magnetic field.</p> <h3 style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; "> <a name="Heading3">Example: Problem 30.10</a></h3> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> At the surface of a pulsar, or neutron star, the magnetic field may be as strong as 10<sup>8</sup> T. Consider the electron in a hydrogen atom on the surface of the neutron star. The electron is at a distance of 0.53 x 10<sup>-10</sup> m from the proton and has a speed of 2.2 x 10<sup>6</sup> m/s. Compare the electric force that the proton exerts on the electron with the magnetic force that the magnetic field of the neutron star exerts on the electron. Is it reasonable to expect that the hydrogen atom will be strongly deformed by the magnetic field ?</p> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> The electron in a hydrogen atom is at a distance r equal to 0.53 x 10<sup>-10</sup> m from the proton. The electric force acting on the electron is equal to</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3008.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.7)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> The maximum magnetic force acting on the electron occurs when the direction of the electron is perpendicular to the direction of the magnetic field. The maximum magnetic force is equal to</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3009.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.8)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> Comparing eq.(30.7) and eq.(30.8) we conclude that the magnetic field is significantly stronger hat the electric field, and we expect that the orbits of the electrons are strongly affected by the intense magnetic field.</p> <h2 style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; "> <a name="Heading4">30.2. The Biot-Savart Law</a></h2> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> The definition of the magnetic force showed that two moving charges experience a magnetic force. In other words, a moving charge produces a magnetic field which results in a magnetic force acting on all charges moving in this field.</p> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> A current flowing through a wire is equivalent to a collection of electrons moving with a certain velocity along the direction of the wire. Each of the moving electrons produces a magnetic field that is given by eq.(30.5). Consider a small segment of the wire with a length dL (see Figure 30.2). At any given time, a charge dq will be located in this segment. The magnetic field, dB, generated by this charge at point P is equal to</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3010.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.9)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> where v is the velocity of the charge carriers. The time dt that it takes for all original charge carriers to leave the segment dL is given by</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3011.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.10)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> The current I in the wire can now be obtained easily</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3012.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.11)</span><br /> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <br /> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3013.gif" /></center> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <b>Figure 30.2. Calculation of magnetic field produced by an electric current.</b> <p> </p> </center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">This equation can be rewritten as</span> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3014.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.12)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> and substituted into eq.(30.9):</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3015.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.13)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> Equation (30.13) is called the <b><u>Biot-Savart Law</u></b>.</p> <h3 style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; "> <a name="Heading5">Example: Problem 30.33</a></h3> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> Helmholtz coils are often used to make reasonably uniform magnetic fields in laboratories. These coils consist of two thin circular rings of wire parallel to each other and on a common axis, the z-axis. The rings have a radius R and they are separated by a distance which is also R. These rings carry equal currents in the same direction. Find the magnetic field at any point on the z-axis.</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3016.gif" /></center> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <b>Figure 30.3. Calculation of magnetic field produced by one ring.</b><br /> </center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">The first step to calculate the field of a pair of Helmholtz coils is to calculate the magnetic field produced by each ring. Suppose the ring is located in the x-y plane and we are interested in the field at point P, a distance z above the x-y plane (see Figure 30.3). The net magnetic field of the ring at point P will be directed along the z-axis. The magnitude dB of the magnetic field produced by a small segment of the ring with length dL is equal to</span> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3017.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.14)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> To obtain eq.(30.14) we have used the fact that for any point on the ring, the position vector r is perpendicular to the direction of dL. The z-component of the magnetic field dB is equal to</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3018.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.15)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> The magnitude of the position vector r is related to R and z:</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3019.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.16)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> The angle a is also related to R and z:</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3020.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.17)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> Combining eqs.(30.15), (30.16) and (30.17) we obtain</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3021.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.18)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> Integrating eq.(30.18) over the whole ring we obtain for the total field generated by the ring</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3022.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.19)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> Figure 30.4 shows the magnetic field generated by one coil with a radius of 1 m, located at z = 0 m.</p> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> To find the field generated by a pair of Helmholtz coils, we assume that the coils are centered at z = 0 and at z = R. The magnetic field generated by the coil located at z = 0 is given by eq.(30.19). The magnetic field generated by the coil located at z = R is given by</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3023.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.20)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> The total field on the axis of a pair of Helmholtz coils is equal to the sum of the field generated by coil 1 and the field generated by coil 2:</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3024.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.21)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> The total magnetic field generated by a pair of Helmholtz coils is shown in Figure 30.5 where also the contributions of the two coils are shown individually. We observe that the field is very homogeneous between the coils (0 < z < R).</p> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> </p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3025.gif" /></center> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <b>Figure 30.4. Magnetic field generated by a coil with R = 1 m.</b> <p> </p> </center> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3026.gif" /></center> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <b>Figure 30.5. Magnetic field generated by a pair of Helmholtz coils.</b> <p> </p> </center> <h3 style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; "> <a name="Heading6">Example: Problem 30.22</a></h3> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> A very long wire is bent at a right angle near its midpoint. One branch of it lies along the positive x-axis and the other along the positive y-axis (see Figure 30.6). The wire carries a current I. What is the magnetic field at a point in the first quadrant of the x-y plane ?</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3027.gif" /></center> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <b>Figure 30.6. Problem 30.22</b> <p> </p> </center> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3028.gif" /></center> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <b>Figure 30.7. Field generated by wire.</b><br /> </center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">The first step to solve this problem is to look at the magnetic field produced by this single wire (see Figure 30.7). The direction of the magnetic field generated by a small segment of the wire is pointing out of the paper. The magnitude of the field, dB, is equal to</span> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3029.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.22)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> The position x of the segment under consideration is determined by the angle a:</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3030.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.23)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> or</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3031.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.24)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> From eq.(30.24) we can obtain a relation between dx and da:</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3032.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.25)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> Furthermore,</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3033.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.26)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> Substituting eq.(30.25) and eq.(30.26) into eq(30.22) we obtain</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3034.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.27)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> The total field can be obtained by integrating eq.(30.27) over the wire. The integration limits are</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3035.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.28)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> and</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3036.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.29)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> The result of the integration is</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3037.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.30)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> The field of the vertical wire can be obtained in a similar fashion:</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3038.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.31)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> The magnitude of the total field is thus equal to</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3039.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.32)</span> <h2 style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; "> <a name="Heading7">30.3. The magnetic dipole</a></h2> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> The magnetic field on the axis of a current loop was discussed in Problem 30.33. At large distances from the current loop (z >> R) the field is approximately equal to</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3040.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.33)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> which shows that the magnetic field strength decreases as 1/z<sup>3</sup>. This dependence of the magnetic field strength on distance is similar to the dependence observed for the electric field strength of an electric dipole:</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3041.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.34)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> Equation (30.33) is often rewritten as</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3042.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.35)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> where</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3043.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.36)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> is called the magnetic dipole moment of the loop. In general, the dipole moment of a current loop is equal to</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3044.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.37)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> Magnetic dipole moments exist for objects as small as electrons and as large as the earth.</p> <h3 style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; "> <a name="Heading8">Example: Problem 30.44</a></h3> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> An amount of charge Q is uniformly distributed over a disk of paper of radius R. The disk spins about its axis with angular velocity [omega]. Find the magnetic dipole moment of the disk.</p> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> The first step to solve this problem is to determine the dipole moment of a ring of the disk, with radius r and with a width dr. The amount of charge dq on this ring is equal to</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3045.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.38)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> The angular velocity of the disk is [omega] and its period T is equal to</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3046.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.39)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> During one period the charge dq will pass any given point on the ring. The current dI is thus equal to</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3047.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.40)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> The magnetic dipole moment du of the ring is equal to</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3048.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.41)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> The total dipole moment of the disk can be found by integrating eq.(30.41) between r = 0 and r = R:</p> <center style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> <img border="1" src="http://teacher.pas.rochester.edu/phy122/Lecture_Notes/Chapter30/Chapter3049.gif" /></center> <span style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; ">(30.42)</span> <p style="color: rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: medium; "> </p>
Colleges are sharing lecture notes, study material, file, assignment etc.
Ask any study related doubt and get answered by college students and faculty.
College student sharing a great video to help peers study.
Access previous year papers for various courses.
Info. update by students of the respective college only.