Answer
$\text { By the right-hand rule, the direction of } \vec{B}_i \text { at } t=20 \mathrm{~s} \text { is out of the page. }$
Work Step by Step
$\text { By the right-hand rule, the direction of } \vec{B}_i \text { at } t=20 \mathrm{~s} \text { is out of the page. }$
