Question

Find theIn the circuit shown in Fig, switch $S_1$ was closed for a long time. At time $t=0$ the switch is opened. Angular frequency of oscillation of the charge on the capacitor :

• A. $100rad{s}^{-1}$
• B. $200rad{s}^{-1}$
• C. $300rad{s}^{-1}$
• D. $400rad{s}^{-1}$

Answer 1

The correct option is B $200rad{s}^{-1}$

When the switch is open the equivalent inductance,

$L_{eq}=\frac{L_2\times L_3}{L_2+L_3}+L_1$
$=\frac{200\times 200}{400}+400=500mH,$
$andcapacitanceC=50uF,$

therefore frequency of oscillation would be,

$f=\frac{1}{\sqrt{LC}}=\frac{1000}{\sqrt{25}}=200rad{s}^{-1}$