答案 A右边的导线在A点的磁感应强度：B1=(μ0I/4πL)(cos90-cos135)=(μ0I/4πL)(1+√2/2)下边的导线在A点的磁感应强度：B2=(μ0I/4πL)(cos45-cos90)=(μ0I/4πL)(√2/2-1)故A点磁感应强度： B=B1+B2=√2(μ0I/4πL)
