A car battery is charged by a 12 V supply, and energy stored in it is 7.20 $$\times$$ 10⁵ J. The charge passed through the battery is -

If n, e, $$\tau$$ and m have their usual meanings, then the resistance of a wire of length l and cross-sectional area A is given by -

Two sources of equal emf are connected in series. This combination is, in turn connected to an external resistance R. The internal resistance of two sources are r₁ and r₂ (r₂ > r₁). If the potential difference across the source of internal resistance r₂ is zero, then R equals to -

The equivalent resistance between A and B of the network shown in figure is