試題詳解

47. A typical small flashlight contains two batteries, each with an emf of 1.5 V, connected in series with a bulb having resistance 17 ohms. The internal resistance is negligible. The batteries last for 5.0 h. Which of the following values most closely approximates the total energy delivered to the bulb?
(A) 9000 J
(B) 7000J
(C) 5000 J
(D) 2000 J
(E) 600 J