Question

A resistance of 10 $\Omega$ capacitance of 0.1$\mu$F and an inductance of 2mH are connected in series across source of alternating emf of variable frequency. At that frequency does maximum current flow?

• A. 11.25 kHz
• B. 23.76 kHz
• C. 35.46 kHz
• D. 46.72 kHz

Answer 1

The correct option is A 11.25 kHz

$X_L=X_c;L\omega$ =$\frac{1}{\omega C}$
$f=\frac{1}{2\pi }\frac{1}{\sqrt{LC}}=\frac{1}{2\pi }\frac{1}{\sqrt{2\times {10}^{-3}\times 0.1\times {10}^{-6}}}$
$f=\frac{1}{2\pi }\frac{1}{\sqrt{2\times {10}^{-10}}}=\frac{{10}^5}{2\times 3.14\times 1.414}=11.25kHz$