PHYS 142 Lecture Notes - Lecture 30: Rlc Circuit, Phasor, Hypotenuse
25 Mar 2015
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Phys 142: electromagnetism and optics - lecture 30 : rlc circuits, resonance, and power. The circuit shown, where a resistor, inductor, and capacitor are in series, is called a series rlc circuit. The instantaneous current of all three elements is the same: i = ir = il = ic. The sum of the instantaneous voltages matches the emf: The length of the emf phasor, 0 hypotenuse of a right triangle. If vl vc, which we"ve assumed, then the instantaneous the emf by a. Based on the right-triangle, the square of the peak voltage is: current phase angle f . Consequently, the peak current in the rlc circuit is: i lags. The phase angle f between the emf and the current is: Suppose we vary the emf frequency w while keeping everything else constant. There is very little current at very low or very high frequencies. I is maximum when xl = xc, which occurs at the resonance frequency:
