Question

obtain an expression for effective emf and internal resistance of two cells connected in series​

Answer 1

Answer:

$\\\tt (v_{1} + v_{2})- I(r_{1}+r_{2})$

Explanation:

Let the cell have an EMF of one cell as $\\\tt V_{1}$ and other cell be $\\\tt V_{2}$

internal resistances of $\\\tt r_1$ and $\\\tt r_2$ respectively.

Let them produce a  net current of $\\\tt I$

Now,

For cell 1:

Voltage =   $\\\tt V_{1}- Ir_{1}$

and for r cell 2:

Voltage = $\\\tt V_{2}- Ir_{2}$

Effective EMF = sum of voltages.

= $\\\tt (v_{1} + v_{2})- I(r_{1}+r_{2})$