【简答题】
A、A.<img src="https://img.ppkao.com/2018-08/lina/2018082815072586879.jpg" />r /> B.<img src="https://img.ppkao.com/2018-08/lina/2018082815073054092.jpg" />r /> C.<img src="https://img.ppkao.com/2018-08/lina/2018082815073512842.jpg" />r /> D.<img src="https://img.ppkao.com/2018-08/lina/2018082815074194166.jpg" />
A、在一半径R=1.0cm的无限长半圆柱形金属薄片中,自上而下通有电流I=5.0A,如图所示。求圆柱轴线上任一点P处的磁感应强度。r /> <img src="https://img.ppkao.com/2018-10/yuanhao/2018100917260958328.jpg" />