Answer
$i_1 = 0$
Work Step by Step
When the switch is reopened, the branch with the battery is essentially cut off from the circuit. Therefore, no current flows through $R_1$.
$i_1 = 0$
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.