13. John uses a multi-meter to measure the voltage across the battery when the switch S is open, and finds it is 1.5 Volt. When the switch is closed, and the battery is connected to a 10 Ω resistor, he finds the voltage across the battery is 1.25 Volt. What's the internal resistance of the battery?
(A)8.33 Ω
(B)2.0 Ω
(C)1.67 Ω
(D)2.5 Ω
(E)None of the above
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統計: 尚無統計資料
統計: 尚無統計資料