JEE Main 2026 · 6 Apr · Shift 2 · Physics Q49

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PhysicsInteger+4 / -1Question 49 of 75

Two cells of emfs 1 V and 2 V and internal resistance 2 Ω and 1 Ω, respectively connected in parallel, gave a current of 1 A through an external resistance. If the polarity of one cell is reversed, then value of current through the external resistance will be $\dfrac\alpha5$ A. The value of $\alpha$ is ________.

Your answer

Answer and worked solution

Official answer: 3

Parallel cells.
$E_{eq}=\frac{\frac12+\frac21}{\frac12+\frac11}=\frac53\text{ V},\qquad r_{eq}=\frac23\ \Omega.$
A current of 1 A gives $R=\tfrac53-\tfrac23=1$ Ω.

One cell reversed.
$E_{eq}=\frac{\left|\frac21-\frac12\right|}{3/2}=1\text{ V},\qquad I=\frac1{1+\frac23}=\frac35\text{ A}.$

Answer: 3

Topics:EMF and internal resistance

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JEE Main 2026 · 6 Apr · Shift 2, Physics question 49