When two identical batteries of internal resistance `1Omega` each are connected in series across a resistor R, the rate of heat produced in R is `J_1`. When the same batteries are connected in parallel across R, the rate is ``J_2 = 2.25 J_2` then the value of R in `Omega` is

Two identical batteries, each of EMF 2V and internal resistance r =1Omega are connected as shown. the maximum power that can be developed across R using these batteries is :

Two indentical batteries, each of emf 2V andinternal resistance r=1Omega are connected as shown. The maximum power that can be developed across R using these batteries is

Two indentical batteries, each of emf 2V andinternal resistance r=1Omega are connected as shown. The maximum power that can be developed across R using these batteries is

Two cells of internal resistance r_1 and r_2 and of same emf are connected in series across a resistor of resistance R. If the terminal potential difference across the call of internal resistance r_1 is zero , then the value of R is

A galvanometer, together with an unknown resistance in series, is connected across two identical batteries of each 1.5 V . When the batteries are connected in series,the galvanometer records a current of 1 A , and when the batteries are connected in parallel, the current is 0.6 A . In this case, the internal resistance of the battery is 1//'**' Omega . What is the value of '**'?