An oscillating circuit consists of a capacitor with capacitance C, a coil of inductance L with negligible resistance, and a switch. With the switch disconnected, the capacitor was charged to a voltage Vrn and then at the moment t = 0 the switch was closed. Find:
(a) The current I (t) in the circuit as a function of time;
(b) The emf of self-inductance in the coil at the moments when the electric energy of the capacitor is equal to that of the current in the coil.