試題詳解

28. For a long ideal solenoid having a circular cross-section, the magnetic field strength within the solenoid is given by the equation B(t) = 5.0t[T], where t is time in seconds. If the induced electric field outside the solenoid is 1.1 V/m at a distance of 2.0 m from the axis of the solenoid, find the radius of the solenoid.
(A) 30.2m
(B) 15.4m
(C) 6.4m
(D) 2.4m
(E) 0.9m