I ALTERNATING CURRENTS 



analysis. The formulas and equations which follow apply to 



sine waves of current and voltage, unless otherwise specified. 



The sine wave may be produced graphically as follows: Draw 



a circle, Fig. 2, whose radius A is equal to the maximum value of 



FIG. 2. Graphical construction of a sine wave. 



the sine wave. Divide the circumference of this circle into any 

 number of equal parts, in this case 12, and number them 

 0, 1, 2 . . . 12. Also draw a horizontal line ab, which, if 

 extended, would pass through the center of the circle. Divide 



FIG. 3. Numerical values of the ordinates of sine waves for definite an^los. 



ab into the same number of equal parts as there are on the 

 circumference of the circle, and give the points corresponding 

 numbers. Erect an ordinate or perpendicular at each point. 

 Project the points on the circle horizontally until they meet 



