如图3所示,一个带电量为q的点电荷位于一边长为l的正方形abcd的中心线上,q距正方形l/2,则通过该正方形的电场强度通量大小等于:( )<img src="https://zk.995w.com/lqwvjeImg/3b/3b54311d0179c0aa1da799bca60a6faf.png" style="font-size: 20px;" ><br>·<img src="https://zk.995w.com/lqwvjeImg/99/994007e199e79b01094a011db20f276d.png"style="width:30px;height:45px;">.<br>·<img src="https://zk.995w.com/lqwvjeImg/24/246fd13ccf764258de706519f2018b12.png"style="width:30px;height:45px;">.<br>·<img src="https://zk.995w.com/lqwvjeImg/62/629525e4d0783a61c4221a36d9462843.png"style="width:37px;height:45px;">.<br>·<img src="https://zk.995w.com/lqwvjeImg/f4/f4ac885831064e5184aa29cd6ada2684.png"style="width:38px;height:45px;">.