One electric cell (having emf 2 V and internal resistance 0.1 Ω) and another electric cell (having emf 4 V and internal resistance 0.2 Ω) are connected in parallel to each other. Then their equivalent emf will be V.

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Accepted Answer

(3) 2.67. Given: ε₁ = 2 V, r₁ = 0.1 Ω; ε₂ = 4 V, r₂ = 0.2 Ω; like terminals joined in parallel. Idea: for two cells in parallel, ε_eq = (ε₁r₂ + ε₂r₁)/(r₁ + r₂), an average of the emfs with weights r₂ and r₁. ε_eq = (2×0.2 + 4×0.1)/(0.1 + 0.2) = (0.8)/(0.3). ε_eq = 2.67 V, which lies between 2 V and 4 V as it must. So the equivalent emf is 2.67 V.

One electric cell (having emf 2 V and internal resistance 0.1 Ω) and another electric cell (having emf 4 V and internal resistance 0.2 Ω) are connected in parallel to each other. Then their equivalent emf will be ______ V.

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Why the other options are wrong