一电场强度为<img src="/lqwvjeImg/15/1523b1e6a103b19d91e5639d72d31130.png"style="width:16px;height:20px;">的均匀电场,<img src="/lqwvjeImg/15/1523b1e6a103b19d91e5639d72d31130.png"style="width:16px;height:20px;">的方向与沿x轴正向,如图<img src="/lqwvjeImg/da/daa6ea4fb65b4e6110a425a2c00032b8.png"style="width:156px;height:113px;">所示.则通过图中一半径为R的半球面的电场强度通量为 ( )<br>· <img src="/lqwvjeImg/9b/9b161a4503d5b31fbae8486aa67407dc.png"style="width:13px;height:12px;">R2E<br>· <img src="/lqwvjeImg/9b/9b161a4503d5b31fbae8486aa67407dc.png"style="width:13px;height:12px;">R2E / 2<br>· 2<img src="/lqwvjeImg/9b/9b161a4503d5b31fbae8486aa67407dc.png"style="width:13px;height:12px;">R2E<br>· 0