The Theory and Practice of Absolute Measurements in Electricity and Magnetism, Volume 2, Part 1Macmillan and Company, 1893 - Electric measurements |
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Common terms and phrases
Ampère's angular axes axis calculated centre circle circuit circular coefficients coil components conductor coordinates corresponding couple cross-section curve deflection denote differential direction cosines displacement distance distribution ds ds effect electric Electro electrokinetic energy electromagnetic electromotive force element ds ellipsoid equal equations experiments expression filament finite given gives gyrostat Hence inductive capacity integral kinetic energy length line integral lines of force magnetic field magnetic force magnetic induction magnetic moment magnetic potential magnetic shell magnetometer medium ment motion mutual induction needle obtained parallel particles plane position potential energy produced quantity R₁ radius result right angles rotation round self-induction shown in Fig solenoid solid angle suppose surface theorem theory tion total induction turns unit vector potential velocity wire zero Κμ ән
Popular passages
Page 230 - ... which are balanced by centrifugal force of the circular motions are equal, while the luminiferous motions are unequal. The absolute circular motions being therefore either equal or such as to transmit equal centrifugal forces to the particles initially considered, it follows that the luminiferous motions are only components of the whole motion ; and that a less luminiferous component in one direction, compounded with a motion existing in the medium when transmitting no light, gives an equal resultant...
Page 230 - For instance, in a medium possessing it, particles in a straight line parallel to the lines of magnetic force, displaced to a helix round this line as axis, and then projected tangentially with such velocities as to describe circles, will have different velocities according as their motions are round in one direction (the same as the nominal direction of the galvanic current in the magnetizing coil) or in the contrary direction. But the elastic reaction of the medium must be the same for the same...
Page 79 - The deflection experiments are, as stated above, to be performed with several magnets, and when the period of oscillation of each of these has been determined, the magnetometer should be replaced on its stand, and the deflection experiments repeated, to make sure that the magnets have not changed in strength in the meantime.
Page 70 - It consists in finding (1) the angle through which the needle of a magnetometer is deflected by a magnet placed in a given position at a given distance, (2) the period of vibration of the magnet when suspended horizontally in the earth's field, so as to be free to turn round a vertical axis. The first operation gives an equation involving the ratio of the magnetic moment of the magnet to the horizontal component H of the terrestrial magnetic force, the second an equation involving the product of...
Page 74 - Let us consider the force acting on one pole, say the red pole of the needle. The red pole of the magnet exerts on it a repulsive force, and the blue pole an attractive force. Each of these forces has the value...
Page 75 - Still another position of the deflecting magnet relatively to the needle may be found a convenient one to adopt. The magnet may be placed still in the east and west line, but with its centre vertically above the centre of the needle.
Page 72 - ... placed with its length in the magnetic north and south line, and the lamp should be so placed that the incident and reflected rays of light are in an east and west vertical plane, and that the spot of light falls near the middle of the scale. To avoid errors due to variations of length in the scale, it should be glued to the wooden backing which carries it, not simply fastened with drawing pins as is often the case. The magnetometer having been thus set up, four or five magnets, each about locms....
Page 179 - ' that is, the ratio, which the theory indicates must be vanishingly small, is equal to the ratio of the number of turns in the circuit to the number of circuits in the solenoid.
Page 71 - Thomson's reflecting galvanometer, from the mirror to a scale attached to the lamp-stand, and facing the mirror. The lamp and scale are moved nearer to or farther from the mirror, until the position at which the image of the cross-wire of the slit is most distinct is obtained. It is convenient to make the horizontal distance of the mirror from the scale for this position if possible one metre.
Page 77 - ... the true period is obtained by taking the mean of the results of a sufficient number of observations, and from this the value of the product of m and H can be calculated.