An LC circuit has a capacitor with C = 0.2 uF and a solenoid with inductance L = 3 mH. Initially the capacitor is fully charged and has a voltage across its plates of 2 V. The capacitor then begins to discharge. What is the magnitude of the current in the circuit when the voltage across the capacitor is 1 V?

Respuesta :

Answer:

The magnitude of the current in the circuit is 0.01159 A.

Explanation:

Given that,

Capacitor [tex]C = 0.2\mu F[/tex]

Inductance [tex]L=3 mH[/tex]

Voltage V = 2 V

We need to calculate the energy when the capacitor is charged

Using formula of energy

[tex]E=\dfrac{1}{2}\dfrac{q^2}{C}[/tex]

[tex]E=\dfrac{1}{2}\times\dfrac{C^2V^2}{C}[/tex]

[tex]E=\dfrac{1}{2}\timesCV^2[/tex]

Put the value into the formula

[tex]E=\dfrac{1}{2}\times0.2\times10^{-6}\times4[/tex]

[tex]E=4\times10^{-7}[/tex]

When the capacitor is discharged

Using formula of energy

[tex]E=\dfrac{1}{2}LI^2[/tex]

[tex]4\times10^{-7}=\dfrac{1}{2}\times3\times10^{-3}\times I^2[/tex]

[tex]I^2=\dfrac{2\times4\times10^{-7}}{3\times10^{-3}}[/tex]

[tex]I=\sqrt{0.00027}[/tex]

[tex]I=0.0164\ A[/tex]

rms value of current,

[tex]I_{rms}=\dfrac{I_{0}}{\sqrt{2}}[/tex]

[tex]I_{rms}=\dfrac{0.0164}{\sqrt{2}}[/tex]

[tex]I_{rms}=0.01159\ A[/tex]

Hence, The magnitude of the current in the circuit is 0.01159 A.

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