Two cells of the same e.m.f. E but internal resistance `r_1` and `r_2` are connected in series to an external resistor R (fig. EP 3.25). What should be the value of R so that the potential difference across the terminals of the first cell becomes zero?

n cells of e.m.f E and internal resistance r are connected in series with an external resistance R . the current will increase n times that of a single cell, if

A cell of emf 2 V and internal resistance 0.1Omega is connected to 3.9Omega external resistance. What will be the potential difference across the terminals of the cell?

A cell of e.m.f. E an internal resistance r is connected across an external resistance R. Plot a graph showing the variation of P.D. across R, verses R.

A number of identical cells, n , each of e.m.f. E, internal resistance r connected in series are charged by a d.c. source of e.m.f. E', using a resitor R Deduce the expresison for the charging current and the potential difference across the combination of the cells.

n cells, each having emf. E and internal resistance r are connected in parallel. What is the net internal resistance of the combination?

A battery of e.m.f E and internal resistance r sends a current I_1 and I_2 , when connected to an external resitance of R_1 and R_2 respectively. Find the e.m.f and internal resistance o the battery.

Two cells of emf 1V and 2V and internal resistance 2 ohm and 1 ohm are connected first in series then in parallel. what should be the external resistance in the circuit so that the current through the resistance be the same in the two cases?