Question

. Two cells each of emf E and internal resistance r are connected parallel across a resistor R. The power dissipated in the resistor is maximum if
R = r R = 3r/2
R = 2r R = r/2ans

Answer 1

Answers:R=r/2

Explanation: first of all You should know that parallel cells just increase the capacity of the cell(means life) but keeps the voltage same as of the single cell emf.

So for max. Power

P=E^2/4R (r=R)

Now for your question 2 cells have internal resistance of r and connected in parallel so equivalent internal resistance is r/2

So here is our answer

R=r/2.