Question

An LCR circuit has L = 10 mH, $R = 3\Omega$ , and $C = 1\,\mu F$ connected in series to a source of $15\,cos\,\omega t$ volt . The current amplitude at a frequency that is 10% lower than the resonant frequency is

• A. 0.5 A
• B. 0.7 A
• C. 0.9 A
• D. 1.1 A

Answer 1

Answer: (B)

$c_v=\frac{90}{100}c_{v_0}=\frac{90}{100}x\frac{1}{\sqrt{LC}}=9000\,rad/s$
$i_0=\frac{E_0}{\sqrt{R^2\left(\omega\,L-\frac{1}{\omega\,C}\right)^2}}$