Two identical cells each of emf 1.5 V are connected in series across a 10Ω resistance. An ideal voltmeter connected across 10Ω resistance reads 1.5 V . The internal resistance of each cell is _____ Ω

Question

Two identical cells each of emf 1.5 V are connected in series across a 10Ω resistance. An ideal voltmeter connected across 10Ω resistance reads 1.5 V . The internal resistance of each cell is _____ Ω .

TestHub · Accepted Answer

Let R 1 ​ = 10Ω . Using V = i R i = ( 10 + 2 r 3 ​ ) The voltmeter reading is V ′ = 1.5 V . Thus, i R 1 ​ = V ′ ⇒ 10 × 10 + 2 r 3 ​ = 1.5 ⇒ 20 = 10 + 2 r ⇒ 2 r = 10 ⇒ r = 5Ω

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