用完全相同的导线分别制成半径为<img src="https://p.ananas.chaoxing.com/star3/origin/0857d95856905634d791af0e81cfdbd7.jpg" alt="0857d95856905634d791af0e81cfdbd7.jpg">的两个圆环，将圆环放在磁感应强度为<img src="https://p.ananas.chaoxing.com/star3/origin/9c9c27a65919f701b11359895793ffcd.jpg" alt="9c9c27a65919f701b11359895793ffcd.jpg">的均匀磁场中，<img src="https://p.ananas.chaoxing.com/star3/origin/9c9c27a65919f701b11359895793ffcd.jpg" alt="9c9c27a65919f701b11359895793ffcd.jpg">与环面都垂直．当<img src="https://p.ananas.chaoxing.com/star3/origin/9c9c27a65919f701b11359895793ffcd.jpg" alt="9c9c27a65919f701b11359895793ffcd.jpg">随时间发生变化时，两环中的感应电流分别为<img src="https://p.ananas.chaoxing.com/star3/origin/4252a527b2fd112ff6dc22e36fb5849a.jpg" alt="4252a527b2fd112ff6dc22e36fb5849a.jpg">，其比值<img src="https://p.ananas.chaoxing.com/star3/origin/b919ca86e5d3264162954140b7adb6cd.jpg" alt="b919ca86e5d3264162954140b7adb6cd.jpg">为［        ］