A Handbook of Electrical Testing

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E. & F. N. Spon, 1892 - Electric measurement - 576 pages
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Page 20 - At this moment, the strength of the current is proportional to the sine of the angle through which the coil has been turned.
Page 153 - ... boilingpoint ; the salt, which is a nearly insoluble white powder, should be well washed in distilled water, and care should be taken to obtain it free from the mercuric sulphate (persulphate), the presence of which may be known by the mixture turning yellowish on the addition of water. The careful washing of the salt is a matter of essential importance, as the presence of any free acid, or of persulphate, produces a considerable change in the electromotive force of the cell.
Page 230 - ... hollow, circular ring. From this ring proceed upwards two brass tubes about five or six inches in length. Down these brass tubes pass the copper electrodes or rods, and these rods are insulated from the tubes at the top and bottom by ebonite insulators. The insulator at the bottom of the tube, where it enters the ring, is a simple collar, that at the top has the form of a funnel corrugated on its outer surface. The use of this funnel will be referred to presently. The actual resistance-coil is...
Page 85 - The total resistance of a parallel circuit is equal to the reciprocal of the sum of the reciprocals of the individual resistances of the circuit.
Page 151 - J inch diameter and 8 inches long in the limb, has four side tubes (see PI. V. fig. 2). The two top ones, A and B, lead to two reservoirs Z and C, and the bottom ones C and D are drainage-tubes. These side tubes are closed by glass taps. The whole is mounted on a vertical board, with a pair of test-tubes between the limbs. Suppose, now, a Daniell's cell is to be formed with solutions of zinc sulphate and copper sulphate, and that the zinc-sulphate solution is the denser. The left-hand reservoir SZ...
Page 517 - T6 will be obtained. The resistance of the wires is practically nil. In testing the strength of a current in milliwebers, the standard cell is connected to A and B, and both plugs being removed from the plug-holes a, 6, the key K is depressed. There is then in circuit a total resistance of 1070", viz., 750 + 320. As the electromotive force of the standard cell is 1'07 volts, the resulting deflection of the Galvanometer-needle (which is about 30) will be due to a current of 1-07 .„„ = '001 weber,...
Page 49 - The mirror is placed in the axle of a coil of wire, some four or five inches across, which completely surrounds it, so that the needle is always under the influence of the coil at whatever angle it is deflected to. A beam of light from a lamp placed behind a screen about three feet distant from the coil falls on the little mirror, the bottom of which is slightly in advance of the top, and is reflected back on to a graduated scale placed just above the point where the beam of light emerges from the...
Page 152 - U-tube with the denser zinc-sulphate solution ; then insert the zinc rod and fit it tightly by the rubber cork P. Now, on opening the tap C the level of the liquid will begin to fall in the right-hand limb but be retained in the closed one. As the level commences to sink in the right-hand limb, by opening the tap B...
Page 435 - Fahrenheit, and the resistance be increased a certain amount by a rise of one degree in temperature, it will be increased by the next degree of rise at the same rate per cent., calculated on the original resistance, plus the amount increased by the first degree of rise.
Page 458 - ... WARREN'S METHOD OF FINDING FAULTS TN INSULATED WIRES. By THOMAS SP BRUCE WARREN, Electrician to Hooper's Telegraph Works, Limited. The insulated wire is half wound on one drum and half on another ; the two being perfectly insulated. The surface of the core between the two is perfectly dried. One end of the conductor is attached to one set of quadrants of an electrometer, the zinc pole of a battery being also attached to these quadrants. The other pole of the battery and the second set of quadrants...

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