Question

A $1.5\mu F$ capacitor is charged of $60V$. The charging battery is then disconnected and a $15$mH coil is connected in series with the capacitor so that LC oscillations occurs. Assuming that the circuit contains no resistance. The maximum current in this coil shall be close to.

• A. $1.4$A
• B. $1.2$A
• C. $0.8$A
• D. $0.6$A

Answer 1

Answer: (D)

$0.6$A

Given:

Capacitance, $C=1.5\mu F$

Voltage applied to capacitor, $V=60volts$

Inductance conncted to the capacitor, $L=15mH$

To find: The maximum current in the inducting coil.

The charge stored in the capacitor is given by:

$Q_0=CV$

The maximum current flowing in the series LC circuit is:

$I_{max}=Q_{o}w$

The frequency of a series LC circuit is given by:

$\omega =\frac{1}{\sqrt{LC}}$

Substitute the values in equation of maximum current.

$⟹I_{max}=\left(CV\right)\times \frac{1}{\sqrt{LC}}=$ $\sqrt{\frac{C}{L}}V$
$\therefore$ $I_{max}=\sqrt{\frac{1.5\times {10}^{-6}}{15\times {10}^{-3}}}\times 60=0.6A$
Correct answer is option D.