For a series RLC circuit driven at resonance (omega0 = 1/sqrt(LC)) by a source of amplitude vₘ, the current shows resonance. What is the quality factor Q of the circuit?

omega0*R/L
R/(omega0*C)
C*R/omega0
omega0*L/R

Correct answer: omega0*L/R

Solution

The quality factor of a series RLC circuit is Q = omega0*L/R (also equal to 1/(omega0*C*R) = (1/R)*sqrt(L/C)). It measures the sharpness of the resonance: higher Q means a narrower bandwidth.

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