A cell of internal resistance r drives current through an external resistance R. The power delivered by the cell to the external resistance will be maximum when :-

In the figure shown, what is the current (in Ampere) drawn from the battery ?
You are given: R₁ = 15$$\Omega $$, R₂ = 10 $$\Omega $$, R₃ = 20 $$\Omega $$, R₄ = 5$$\Omega $$, R₅ = 25$$\Omega $$, R₆ = 30 $$\Omega $$, E = 15 V

A 200 $$\Omega $$ resistor has a certain color code. If one replaces the red color by green in the code, the new resistance will be :

For the circuit shown, with R₁ = 1.0W, R₂ = 2.0 W, E₁ = 2 V and E₂ = E₃ = 4 V, the potential difference between the points 'a' and 'b' is approximately (in V):