An LR series circuit has a variable inductor with the inductance defined by 0 st 20 t 20 Find the current i t if the resistance is 0 1 ohm the impressed voltage is E t 4 and 0 0 0 st 20 i t L t Graph i t i t 40 30 20 10 i t 40 30 20 10 20 F t 20 5 10 10 15 20 20 30 25 30 40 t t i t 40 30 20 10 i t 40 30 20 10 5 10 15 10 20 20 30 25 30 40 t