# Hawkins Electrical Guide ...: Questions, Answers & Illustrations; a Progressive Course of Study for Engineers, Electricians, Students and Those Desiring to Acquire a Working Knowledge of Electricity and Its Applications; a Practical Treatise, Volume 1

T. Audel & Company, 1917

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### Contents

 BASIC PRINCIPLES 161 to 161 CURRENT 171

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Page 30 - The flow of the current is proportional to the voltage and inversely proportional to the resistance. The latter depends upon the material, length and diameter of the conductor. Since the current will always flow along the path of least resistance, it must be so guarded that there will be no leakage. Hence, to prevent leakage, wires are insulated, that is, covered by wrapping them with cotton, silk thread, or other insulating material. If the insulation be not effective, the current may leak, and...
Page 88 - The amount of work done by gravity upon the weights in causing them to descend through any distance d was equal to their weight W times this distance. If the weights descended slowly and uniformly, this work was all expended in overcoming the resistance of the water to the motion of the paddle wheels through it ; that is, it was wasted in eddy currents in the water. Joule measured the rise in the temperature of the water and found that the mean of his three...
Page 115 - ... the coil is grasped in the right hand in such a way that the fingers point in the direction in which the current is flowing in the wires, the thumb will point in the direction of the north pole of the helix (see Fig.
Page 74 - X 13 = 650 ohms. 2. The resistance of a conducting wire is inversely proportional to the area of its cross section, and therefore in the usual round wires is inversely proportional to the square of its diameter. Ordinary...
Page 74 - ... it flows ; but the amount of water that runs through will depend not on the pressure alone, but on the resistance it meets with ; for, if the pipe be a very thin one, or choked with sand or sawdust, the water will only run slowly through. Now the metals in general conduct well : their resistance is small ; but metal wires must not be too thin or too long, or they will resist too much, and permit only a feeble current to pass through them. The liquids in the battery do not conduct nearly so well...
Page 3 - Current electricity. This may be defined as the quantity of electricity which passes through a conductor in a given time — or, electricity in the act of being discharged, or electricity in motion. An electric current manifests itself by heating the wire...
Page 30 - If the insulation be not effective, the current may leak, and so return to the source without doing its work. This is known as a short circuit. The conductor which receives the current from the source is called the lead and the one by which it flows back, the return. When wires are used for both lead and return, it is called a metallic circuit; when the...
Page 110 - Copenhagen, showed that a magnet tends to set itself at right angles to a wire carrying an electric current. He also found that the way in which the needle turns, whether to the right or...