Question

1.A serial circuit with resistor of 600 ohm and capacity of 4μF is connected to the source of alternating circuit of 100 V with a voltage equation V=Vmsin 250t.The magnitude of inductor that must be serially installed to the circuit in order to flow the current of 100mA is...H

A.0.1
B.0.2
C.0.4
D.0.8
E.1


2.A straight wire of 120 cm carries directional current of 0.25A.If the space is affected by magnetic field of 0.5T that perpendicular to the current,thus the magnitude of Lorentz force of the wire is...

A.0.15N
B.0.30N
C.0.60N
D.30N
E.60N


3.Magnetic flux produced by magnetic filed B that through perpendicularly a surface of width A is P.If the magnetic field is reduced into B/2,but the width surface enlarged to 2A,then flux produced is...

A.P/4
B.P/2
C.P
D.2P
E.4P