38. A solenoid has an inductance 75 mHand a winding resistance 0.50 Ω. If a battery is connected to the solenoid, how long will the current reach half its final equilibrium value? ( log2 = 0.301,ln 2 = 0.693 )
(A) 0.10 s
(B) 45 ms
(C) 4.6 s
(D) 2.0 s
(E) 26 ms

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統計： A(35), B(1), C(5), D(0), E(5) #2020482