Doubt about circuits with cells having internal resistances
Yes assuming V1 is a non ideal source with an internal resistance (r) in series with a load R. This can be modelled as an ideal source in series with r+R. The voltage delivered to the load will simply be \$V_r=\frac{V_1*R}{R+r}\$.

In order to operate your circuit in the linear region it is recommended that you keep R>>r.

The effective emf of the cell on the other hand may be calculated as follows assuming \$V_1\$ is an ideal source:

$$I = \frac{V_1}{R+r}$$
$$V_{eff}=V_1-(I\times r)$$



EDIT 1

For analysing the internal resistance use this model.







simulate this circuit &ndash; Schematic created using CircuitLab

Here the effective resistance is simply r+R

For your second circuit.







simulate this circuit

Here in this case as you can see the effective resistance becomes (R||R2)+r