In a series RLC circuit at resonance
Correct answer: B. the impedance is minimum and equal to the resistance, so the current is maximum
- A. the impedance is maximum and the current minimum
- B. the impedance is minimum and equal to the resistance, so the current is maximum
- C. the current is zero
- D. the capacitor and inductor can be removed without effect
Explanation
At resonance the inductive and capacitive reactances are equal and cancel, leaving only the resistance to oppose the current, so the current peaks sharply. The resonant frequency is 1 over 2 pi times the square root of LC. Tuning a radio means adjusting a capacitor until the resonant frequency matches the station wanted.
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About AC Through Resistor, Capacitor and Inductor
Alternating current through a resistor, capacitor and inductor involves phase relationships between voltage and current, reactance, impedance and energy transfer. A resistor keeps voltage and current in phase, while a capacitor and inductor produce opposite phase shifts, a distinction used in circuit diagrams and numerical calculations.
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