If a battery is packed in a box and if only two wires from two terminals are given out, how can we decide the positive and negative terininal of the battery ?

Why does the battery discharge when its positive and negative terminals are connected through a conductor ?

___________ spot is seen on the potato around Wire connected to the positive terminal of battery.

What do you called the work done by the chemical force to move unit positive charge from negative terminal to positive terminal of the battery ?

A cell of emf 10 V and internal resistance 3 Omega is connected in parallel with another cell of emf 7V and internal resistance 3/5 Omega, such that their positive terminals are joined together and so there are negative terminals. Their positive terminals are joined with the negative terminal and their negative terminal is joined with the positive terminal of a third cell of emf 20 V with internal resistance 2Omega. The combination can be replaced by a battery of emf E and internal resistance r, then the values of E and R are respectively

One end each of resistance, capacitor C and resistance 2r are connected together. The other ends are respectively connected to the positive terminals of batteries. P, Q. R having respectively emf's E, E and 2E. The negative terminals of the batteries are then connected together. In this circuit, with steady current the potential drop across the capacitor is