题目8单选题
如图所示,在无限长载流直导线附近作一球形闭合曲面S,当曲面S向长直导线靠近时,穿过曲面S的磁通量<img src="https://tihai-oss-cloud.itihey.com/img/e864a0936950cf261ab31c4be1ac9cf5.png">和面上各点的磁感应强度<img src="https://tihai-oss-cloud.itihey.com/img/bbcc8eac94a2fd52216df9a86f3b1279.png">将如何变化?( )<img src="https://tihai-oss-cloud.itihey.com/img/268000a6f2696db7e1282beea1604d3f.jpg">A. <img src="https://tihai-oss-cloud.itihey.com/img/e864a0936950cf261ab31c4be1ac9cf5.png">增大,B也增大B. <img src="https://tihai-oss-cloud.itihey.com/img/e864a0936950cf261ab31c4be1ac9cf5.png">不变,B也不变C. <img src="https://tihai-oss-cloud.itihey.com/img/e864a0936950cf261ab31c4be1ac9cf5.png">增大,B不变D. <img src="https://tihai-oss-cloud.itihey.com/img/e864a0936950cf261ab31c4be1ac9cf5.png">不变,B增大