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Unformatted text preview: Register your iclicker The following 2 iclickers are not registered yet AADF255, FF1CD33 Check if the one is yours and register asap 1 Students with these iclicker IDs have resigned? 103298BA, A27DFF2 Cover the following topics: Magnetic field vector B Magnetic force on a moving charge Magnetic field lines Motion of a charge particle in an uniform Chapter 28 Magnetic Fields 2 magnetic field Magnetic force on a current carrying wire Magnetic torque on a wire loop Magnetic dipole , magnetic dipole moment t Hall effect Cyclotron and Synchrotron particle accelerators 2 An electric field E is produced by an electric charge In contrast, magnetic field B is not produced by magnetic charge. In fact, there is no such thing as magnetic charge (often called magnetic monopole ) Then how magnetic fields can be created? One way to produce a magnetic field is to use moving electrically harged particles. E.g. current in a wire of an lectromagnet Producing Magnetic Field 3 charged particles. E.g. current in a wire of an electromagnet The other way to produce magnetic field is by means of elementary particles such as electrons because these particles have intrinsic magnetic field around them magnetic field is a basic characteristic of each particle (like mass, charge, etc.) Magnetic fields of electrons in certain materials add together to give a net magnetic field. Permanent magnets are made of this type of materials. In most of other materials magnetic fields of electrons cancel out, producing no net magnetic field The magnetic field vector B is defined in terms of the force F it exerts on a charge q which moves with velocity v : We inject the charge q in a region where we wish to determine B at random directions, trying to scan all possible directions. There is one direction for which the force F B on q is equal to zero. This direction is that of B . For all other directions F is not zero and its magnitude is B r The Definition of 4 B qvB F B sin = B v q F B r r r = where is angle between the directions of v and B Furthermore, the direction of F B is always perpendicular to v We can summarize these results with the following vector equation: The Cross/Vector Product of Two Vectors The Cross/Vector Product of Two Vectors c = a b We combine a and b to form a new vector c 1. Magnitude of c : c = absin 2. Direction of c : c is perpendicular to the plane defined by a and b , and the direction is given y the right hand rule: hen fingers 5 by the right hand rule: when fingers sweep a into b , the thumb of the right hand points in the direction of c b a a b v r r r  = Vector Product by Components Vector Product by Components The vector product of two vectors can be calculated using their components , k a j a i a a z y x + + = r , k b j b i b b z y x + + = r b a k c j c i c c z y x r r r = + + = here: z O x y...
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 Fall '08
 IASHVILI

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