Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: McQueen on 01/07/2005 03:45:57
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The Lorentz Force always acts at right angles to the plane vectors containing B and v . This means that it is perpendicular to both these vectors ,it therefore cannot perform work on moving charges in a magnetic field . It can only change the direction of the velocity of motion of the free charges , i.e., it is a centripetal force. One cannot question the veracity of Lorentz’s work, his equations in the form of the Lorentz transformations underpin the Theory of Special Relativity, yet as regards his observation with regard to the Lorentz Force and currents it has to be stated that his conclusions based on the observations of Ampere and Oersetd were false. Lorentz assumed that a homogenous magnetic field was present around a straight wire because of the movement of electrons within the wire , (i.e., the magnetic field was formed at right angles to the direction of movement of the electrons within the wire. Thus if a charged particle is directed at right angles towards a current carrying wire , the charged particle would trace a circle perpendicular to the wire. This might be true but it has nothing to do with the direction of motion of the charged particles , rather it has to do with the fact that when dealing with a current in a wire we are not dealing with the field around a straight wire but that around a circular wire. It has been mathematically proved that the field inside a circular wire is homogenous and that the centripetal Lorentz Force would apply. Take by contrast the field around a bar magnet , if a charged particle is directed at right angles to the magnetic field around a bar magnet the resulting motion of the particle would be extremely complicated ( i.e., it wouldn’t move in a circle ) because the field around a bar magnet is not homogenous it varies in magnitude and direction at every point. Thus the motion of a charged particle in the vicinity of a wire carrying a current is not due to the manner or direction in which the charges are moving inside the wire but due to the circular shape of the wire in which the charges are moving , which results in a homogenous magnetic field.