Physics · Reactance and impedance, LCR series circuit, resonance, power in AC circuits, wattless current
The current flowing through the resistor in a series LCR a.c. circuit, is Now th
The current flowing through the resistor in a series LCR a.c. circuit, is \( \boldsymbol{I}=\varepsilon / \boldsymbol{R} \) Now the inductor and capacitor are connected in parallel and joined in series with the resistor as shown in figure. The current in the circuit is now. (Symbols have their usual meaning)
- A. equal to I
- B. more than I
- C. less than 1
- D. zero
Step-by-step solution
In the initial series LCR circuit at resonance (I = ε/R), the inductive and capacitive reactances cancel, resulting in minimum impedance equal to R. In the modified circuit, the inductor and capacitor are connected in parallel. At the same resonant frequency, the parallel LC combination has infinite impedance (ideally), acting as an open circuit. Thus, the total impedance becomes infinite, and no current flows. Therefore, the current in the circuit is zero.
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