Question 11.SP.8: A, B, and C are three sine ac voltage waveforms of the same ......
A, B, and C are three sine ac voltage waveforms of the same frequency. Sine wave A leads sine wave B by a phase angle of 60° and lags sine wave C by 130°. What is the phase angle between wave B and wave C? Which wave is leading?
Draw the sine waves with phase angles described. A convenient way to draw or measure the phase angle between two sine waves is to compare their zero crossings. Wave A is drawn as the reference beginning at 0° (Fig. 11-22). Wave B is drawn beginning at 60° to indicate that wave A leads wave B by 60°. Wave C is shown beginning at -130° to show that A lags C by that angle. Compare the zero crossings on the horizontal axis of waves B and C as they move toward the positive cycle. B crosses the axis upward at 60°, while C does so at 230°. The phase angle is the phase difference between 230° and 60°, or 170°. Since B crosses the axis before wave C, B leads C.
