Subelement B: Electrical Math— Topic 13: Power Relationships
Question 3-13B5
Element 3 (GROL)What does the power factor equal in an R-L circuit having a 45 degree phase angle between the voltage and the current?
Explanation
The power factor in an AC circuit is defined as the cosine of the phase angle ($\theta$) between the voltage and the current. It represents the ratio of true power (or real power) to apparent power.
Given a phase angle of 45 degrees between the voltage and the current in an R-L circuit, we calculate the power factor as:
Power Factor = cos($\theta$)
Power Factor = cos(45°)
The value of cos(45°) is approximately 0.707.
Therefore, an R-L circuit with a 45-degree phase angle has a power factor of 0.707.
* 0.866 would correspond to a phase angle of 30 degrees (cos 30°).
* 1.0 would indicate a phase angle of 0 degrees, meaning a purely resistive circuit with no reactive component.
* 0.5 would correspond to a phase angle of 60 degrees (cos 60°).
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