An ideal solenoid is 18.5 cm long, has a circular cross-section2.20 cm in diameter, and contains 545 equally spaced thin windings.This solenoid is connected in a series circuit with a 15.0Ω resistor, a battery of internal resistance 5.00 Ω and open-circuit terminal voltage of 25.0 V, and an open switch.
b) How long after closing the switch will it take for the stored energy in the solenoid to reach one-half of its maximum value?