【判断题】对于任意两个随机事件A、B,若B⊂A,则有有P(A-B)=P(A)-P(B)
【简答题】对于任意 A 、 B 事件,均有: P ( A ∪ B ) = P ( A )+ P ( B )-
【判断题】对于任意两个事件A、B,不一定有P(A-B)= P(A)-P(B)成立.
【单选题】A residual magnetic field is always?
A.
Stronger than the magnetic field producing it
B.
Weaker than the magnetisiing field producing it
C.
Equal to the magnetising field producing it
【判断题】Any magnetic field can gives rise to an electric field and any electric field can gives rise to a magnetic field.
【单选题】The diagram shows a straight wire carrying current i in a uniform magnetic field. The magnetic force on the wire is indicated by an arrow but the magnetic field is not shown. Of the following possibil...
A.
opposite the direction of the current
B.
in the direction of force.
【简答题】计算: 小题1:(1)(6分) ; 小题2:(2)(6分) .