EE 2950 Chapter : Chapter 04part2

A coil having an inductance of 6 H and an unknown resistance is connected in series with 
a resistor of 10 Ω to a 120 V dc supply. The time constant of the circuit is 300 ms. When 
steady state conditions have been reached, the supply is replaced instantaneously by a short-circuit. Determine the resistance of the coil, the current flowing in the circuit one second after the shorting link has been placed in the circuit, and the time taken for the current to fall to 10% of its initial value. 

A coil having an inductance of 6 H and an unknown resistance is connected in series with 
a resistor of 10 Ω to a 120 V dc supply. The time constant of the circuit is 300 ms. When 
steady state conditions have been reached, the supply is replaced instantaneously by a shortcircuit. Determine the resistance of the coil, the current flowing in the circuit one second 
after the shorting link has been placed in the circuit, and the time taken for the current to 
fall to 10% of its initial value