A Handbook of Electrical Testing |
Common terms and phrases
a₁ Accuracy attainable adjusted amperes angle approximately arrangement b₁ battery Best Conditions bridge C₁ C₂ cable capacity cent charge circuit condenser conductor resistance connected copper core d₁ Daniell cell deflection obtained degree of accuracy depressed determine discharge deflection divisions E₁ E₂ ebonite electromotive force equal equation equilibrium error example F₁ F₂ fault figure of merit foregoing formula galvano galvanometer needle gutta-percha inserted instrument insulation resistance L₁ latter leakage length lever loop magnet measured megohms mercurous sulphate method microfarads millimetres ohms p₁ Percentage of accuracy plugs position Possible Degree potential produced quadrants quantity R₁ R₂ reading resistance coils S₁ scale screws self-induction short-circuit shown by Fig shunt slide wire slider standard cell sulphate suppose tangent galvanometer temperature terminals total resistance V₁ volts Wheatstone Bridge zero zinc zinc sulphate
Popular passages
Page 574 - Ampere, which is one-tenth of the unit of current of the CGS system of electromagnetic units and which is represented sufficiently well for practical use by the unvarying current which, when passed through a solution of nitrate of silver in water, in accordance with a certain specification, deposits silver at the rate of 0.001118 of a gramme per second.
Page 574 - As a unit of resistance, the international ohm, which is based upon the ohm equal to 10" units of resistance of the CGS system of electromagnetic units, and is represented by the resistance offered to an unvarying electric current by a column of mercury at the temperature of melting ice, 14.4521 grams in mass, of a constant cross-sectional area and of the length of 106.3 centimetres.
Page 575 - The liquid should consist of a neutral solution of pure silver nitrate, containing about 15 parts by weight of the nitrate to 85 parts of water. The resistance of the voltameter changes somewhat as the current passes. To prevent these changes having too great an effect on the current some resistance besides that of the voltameter should be inserted in the circuit. The total metallic resistance of the circuit should not be less than 10 ohms.
Page 574 - In the following specification, the term silver voltameter means the arrangement of apparatus by means of which an electric current is passed through a solution of nitrate of silver in water. The silver voltameter measures the total electrical quantity which has passed during the time of the experiment, and by noting this time, the time average of the current, or if the current has been kept constant, the current itself can be deduced.
Page 176 - Contact is made with the mercury by means of a platinum wire about No. 22 gauge. This is protected from contact with the other materials of the cell by being sealed into a glass tube. The ends of the wire project from the ends of the glass tube ; one end forms the terminal, the other end and a portion of the glass tube dip into the mercury.
Page 176 - Then insert the cork and zinc rod, passing the glass tube through the hole prepared for it. Push the cork gently down until its lower surface is nearly in contact with the liquid. The air will thus be nearly all expelled, and the cell should be left in this condition for at least...
Page 178 - H form, the zinc is replaced by an amalgam of 10 parts by weight of zinc to 90 of mercury. The other materials should be prepared as already described. Contact is made with the amalgam in one leg of the cell, and with the mercury in the other, by means of platinum wires sealed through the glass.
Page 574 - Ampere, which has the value ^ in terms of the centimetre, the gramme and the second of time, and which is represented by the unvarying electric current which, when passed through a solution of nitrate of silver in water in accordance with the specification appended hereto and marked A, deposits silver at the rate of O'OOlllS of a gramme per second.
Page 177 - The Mercurous Sulphate. — The treatment of the mercurous sulphate has for its object the removal of any mercuric sulphate which is often present as an impurity. Mercuric sulphate decomposes in the presence of water into an acid and a basic sulphate. The latter is a yellow substance...
Page 576 - In determining by this method the constant of an instrument the current should be kept as nearly constant as possible, and the readings of the instrument observed at frequent intervals of time. These observations give a curve from which the reading corresponding to the mean current (time- average of the current) can be found. The current, as calculated by the voltameter, corresponds to this reading.