# Elementary magnetism and electricity: prepared in the Extension Division of the University of Wisconsin

McGraw-Hill, 1914 - Science - 212 pages

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Page 205 - An erg is the work done by a force of one dyne acting through a distance of one centimeter ; or unit work is done by unit force acting through unit distance.
Page 132 - constant mass " temperature coefficient of any sample is 0.000597 + 0.000005 1 resistivity in ohms (meter, gram) at t° C. The density is 8 . 89 grams per cubic centimeter. NOTE 2. — The values given in the table are only for annealed copper of the standard resistivity. The user of the table must apply the proper correction for copper of any other resistivity. Hard-drawn copper may be taken as about 2.7 per cent higher resistivity than annealed copper.
Page 195 - ... In the same way the system worked upon may receive energy from the system working in the form of heat, which escapes later, and is no longer available as energy in the system worked upon. 38. Expressions for Energy. Since by definition a system possesses energy only by virtue of work done upon it, the unit of energy is the same as the unit of work, the erg. The dimensions of energy are the same as those of work, [MI?T"*~\.
Page 108 - The mass of any substance liberated by a given quantity of electricity is proportional to the chemical equivalent of the substance. The...
Page 201 - I is in amperes, R in ohms, and t in seconds. ' The mechanical engineering unit of heat is called the British thermal unit, which is abbreviated to Btu A Btu is the heat required to change the temperature of 1 pound of water 1°F.
Page 130 - Because the area of a round wire in circular mils is equal to the square of the diameter in mils, and because the conductivity of wires of the same material are directly proportional to their area expressed in circular mils.
Page 142 - C, if the metal is in the form of a 1 cm. -cube, but since the resistance of a conductor is directly proportional to its length and inversely proportional to its cross-sectional area, it is 1'6 x 100 x 100 = 16 000 microhms = 0 '016 n if the 1 cu.
Page 45 - If a wire through which electricity is flowing is so grasped (Fig. 124,777) with the right hand that the thumb points in the direction of the current flow, the fingers will point in the direction of the magnetic field and vice versa.
Page 200 - This loss as previously explained, is equal to the square of the current multiplied by the resistance. The...
Page 26 - Grasp the wire in the right hand, with the thumb pointing in the direction of the current. The fingers will curl around the wire in the direction of Conductor the magnetic field".