105d. -110

106.

When all the instantaneous values of an alternating voltage or

current (A.C.) are plotted on a time line, marked off in degrees

of rotation, the result is a sine wave.

You will now be shown how to draw a graph of the sine function, commonly called a

sine curve or sine wave.

When a resultant vector is rotated from 0 through 360 (four quadrant), the side

opposite (y vector) increases from zero to maximum positive magnitude in the first

quadrant; decreases from maximum positive magnitude to zero in the second quadrant;

increases to maximum negative magnitude in the third quadrant; and, finally, decreases

back to zero magnitude in the fourth quadrant.

This variation of the y vector can be seen by plotting the magnitudes of the y vector

above or below the horizontal reference line (the X axis) for each degree of rotation of

the resultant vector.

Keep in mind, as you progress through this objective, that the altitude, or magnitude of

the side opposite (the y vector) represents e .... the INSTANTANEOUS value of a

constantly changing voltage or current.

(CONTINUED ON NEXT PAGE)

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