The circuit with a battery, an inductor and a 20 Ohm-resistor can have a battery connected or disconnected depending on which switch is open. The battery is initially connected (switch 1 is closed and switch 2 is open) and then the battery is disconnected and the system evolves in time. You may look at the current from the graph after the switch 2 is closed and switch 1 is open.
What is the inductance of the inductor?
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