Suppose there is a circuit consisting of only resistances and batteries and we have to double (or increase it to n-times) all voltages and all resistances. Show that currents are unaltered. Do this for circuit of Example 3.7 in the NCERT Text Book for Class XII.
Consider a circuit with effective emf Eeff, effective internal resistance Reff and total resistance R as shown in the figure.
The current in this circuit = 
If we increase all the values in the circuit by n, effective emf is nEeff, effective internal resistance is nReff and total resistance is nR.
The current in the final circuit =
= 
2