A battery of e.m.f `epsilon` and internal resistance r is connected to an external resistance R to complete the circuit. Show that the battery of delivers the maximum power to R, when R=r.

A cell of emf (E) and of internal resistance (r ) is connected across an external resistance (R ). Deduce the condition for current in the ciruit to be maximum.

A cell of emf E and internal resistance ® is connected across an external resistance, R. The cell shall drive maximum current through the external resistance R only if

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.