Obtain an expression for the equivalent emf and internal resistance of two cells connected in parallel.

Derive the expression for equivalent emf and equivalent internal resistance of two cells connected in series.

Define internal resistance of a cell.

Obtain an expression for equivalent resistance of two resistors connected in a series combination.

a] Obtain an expression for the equivalent resistance of three resistors connected in series. Also write the expressions for current and voltage in the circuit. b] Mention any two advantages of connecting resistors in series.

Obtain an expression for equivalent resistance of two resistors connected in parallel.

If E_(1) , E_(2),E_(3) ... E_(n) represent emfs of a number of cells of internal resistances r_(1) , r_(2) , ... r_(n) then mention their equivalent emf and internal resistance when these are connected in series.