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In mathematics, a complex number is an element of a number system that extends the real numbers with a specific element denoted i, called the imaginary unit and satisfying the equation =; every complex number can be expressed in the form +, where a and b are real numbers.
Phasor notation (also known as angle notation) is a mathematical notation used in electronics engineering and electrical engineering.A vector whose polar coordinates are magnitude and angle is written . [13] can represent either the vector (, ) or the complex number + =, according to Euler's formula with =, both of which have magnitudes of 1.
Figure 9 is the phase plot. Using the value of f 0 dB = 1 kHz found above from the magnitude plot of Figure 8, the open-loop phase at f 0 dB is −135°, which is a phase margin of 45° above −180°. Using Figure 9, for a phase of −180° the value of f 180 = 3.332 kHz (the same result as found earlier, of course [note 3]).
Lissajous curves can also be generated using an oscilloscope (as illustrated). An octopus circuit can be used to demonstrate the waveform images on an oscilloscope. Two phase-shifted sinusoid inputs are applied to the oscilloscope in X-Y mode and the phase relationship between the signals is presented as a Lissajous figure.
For any complex number written in polar form (such as r e iθ), the phase factor is the complex exponential (e iθ), where the variable θ is the phase of a wave or other periodic function. The phase factor is a unit complex number, i.e. a complex number of absolute value 1. It is commonly used in quantum mechanics and optics.
The field produced by a single-phase winding can provide energy to a motor already rotating, but without auxiliary mechanisms the motor will not accelerate from a stop. A rotating magnetic field of steady amplitude requires that all three phase currents be equal in magnitude, and accurately displaced one-third of a cycle in phase.
A related goal is to find a relation between the magnitude and phase of a complex response function. In general, unfortunately, the phase cannot be uniquely predicted from the magnitude. [ 9 ] A simple example of this is a pure time delay of time T , which has amplitude 1 at any frequency regardless of T , but has a phase dependent on T ...
The complex gain G of this circuit is then computed by dividing output by input: = =. This (unitless) complex number incorporates both the magnitude of the change in amplitude (as the absolute value) and the phase change (as the argument).