题目2单选题
取一闭合积分回路L,使三根载流导线穿过它所围成的面,现改变三根导线之间的相互间距,但不越出积分回路,则: ( )A. 回路L内的<img src="https://tihai-oss-cloud.itihey.com/img/eb3ac237e4828122dff83fdfa113b020.png">不变,L上各点的B不变B. (B)回路L内的<img src="https://tihai-oss-cloud.itihey.com/img/eb3ac237e4828122dff83fdfa113b020.png">不变,L上各点的B改变C. 回路L内的<img src="https://tihai-oss-cloud.itihey.com/img/eb3ac237e4828122dff83fdfa113b020.png">改变,L上各点的B不变D. 回路L内的<img src="https://tihai-oss-cloud.itihey.com/img/eb3ac237e4828122dff83fdfa113b020.png">改变,L上各点的B改变