In an ideal LC oscillator circuit, the total energy is completely electrical at a given instant $t=0

Question

In an ideal LC oscillator circuit, the total energy is completely electrical at a given instant $t=0$. After exactly one-fourth of a time period ($T/4$), the energy of the circuit will be

Professor PC Thomas Classes · Answer

(b) : In an LC circuit, energy oscillates back and forth between the electric field of the capacitor and the magnetic field of the inductor. If the energy is purely electrical (maximum charge on the capacitor) at $t=0$, then at $t = T/4$ (a quarter cycle later), the capacitor is completely discharged, and the current through the inductor is at its maximum. Therefore, the energy is completely magnetic at this instant.