. 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. rires and falls J4ampere. It is thusseen that the rale ofaries from amaximum when thecurrent is least, tozero when the currentis at its , the re-induction being pro-r •:: >:.:. ;. :>:■; -j;, zih. is greatestwhen the current is •:to value, andzero when the cur-reni .vs maxi- mum. 92c3dva ALTERNATING CURRENT DIAGRAMS
. 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. rires and falls J4ampere. It is thusseen that the rale ofaries from amaximum when thecurrent is least, tozero when the currentis at its , the re-induction being pro-r •:: >:.:. ;. :>:■; -j;, zih. is greatestwhen the current is •:to value, andzero when the cur-reni .vs maxi- mum. 92c3dva ALTERNATING CURRENT DIAGRAMS This relation is shown by curves in fig. , and it should be notedthat the rrcerse pressure and current are 90° apart in phase. For thisreason many alternating current problems may be solved graphicallyby the use of right angle triangles, the sides, drawn to some arbitraryscale, to represent the quantities involved, such as resistance, reactance,impedance, etc. Properties of Right Angle Triangles.—In order to under-stand the graphical method of solving alternating current prob-lems, it is necessary to know why certain relations exist betweenthe sides of a right angle triangle. For instance, in every rightangle triangle:. 560* PHASEDIFFERENCE4 90° >J FlG. 1,3QS.—Sine curves showing phase relation between current and reverse pressure of self-induction. This reverse pressure, being proportional to the rate of change in the currentstrength, is greatest when the current is at zero value, and zero when the current is maximum,and in phase is 90° behind the current. The square of the hypothenuse is equal to the sum of the squaresrtyi the other tu-o sides. That is, condensing this statement into the form of an equation: hypothenuse2 = base2 -f- altitude2 (1) the horizontal side being called the base and the vertical side,the altitude. This may be called the equation of the right angle triangle. 1,070 HAWKINS ELECTRICITY Ques. Why is the square of the hypothenuse of a
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