The current in a circuit with a cell of e.m.f 6 V and internal resistance `0.1 Omega` is 2 A. Find the value of the external resistance in it.

5 cells each of e.m.f 1.5 V and internal resistance 0.1 Omega are connected in such a manner that the current in an external resistor of 10 Omega is maximum. Draw the circuit diagram of the combination and calculate the current in the circuit.

A cell of emf E and internal resistance r drives a current of 5 Ampere through an extenal resistance of 8 ohm. The current drops to 4 Ampere when the external resistance is increased to 10.1 ohm. Find the emf E and the internal resistance r of the cell.

Find relation between emf and internal resistance of a cell.

Two coils connected in series have a resistance of 18Omega and when connected in parallel have a resistance of 4Omega . Find the value of individual resistance of the coils.