Question

In series LCR circuit at resonance,

• A. current is maximum and voltage is minimum
• B. current is maximum and voltage is maximum
• C. current is minimum and voltage is maximum
• D. current is minimum and voltage is minimum

Answer 1

Answer: (A)

current is maximum and voltage is minimum

Answer 2

At resonance in a series LCR circuit, the inductive and capacitive reactances cancel out so that the net impedance is minimum (equal to R). Hence, for a given supply voltage, the current is maximum. Also, since the impedance is minimum, the voltage drop across the circuit (which is I·R) is minimized relative to off-resonance conditions.

• At resonance, X_L = X_C so net impedance Z = R (minimum).
• Maximum current: I = V / R.
• Voltage across the circuit (I·R) is minimum due to minimum impedance.