A relay coil has a resistance of 100 Ω and an inductance of 100 mH. A rectangular voltage pulse of amplitude 5 V and duration 5 ms is applied to the coil. If the relay contacts close when the current...

A relay coil has a resistance of 100 Ω and an inductance of 100 mH. A rectangular voltage pulse of amplitude 5 V and duration 5 ms is applied to the coil. If the relay contacts close when the current in the coil reaches 40 mA and open when it drops to 15 mA, determine the length of time for which the contacts remain open.