For the circuit shown in the figure, the current \(I\) will be:

A battery consists of a variable number \(n\) of identical cells (having internal resistance \(r\) each) which are connected in series. The terminals of the battery are short-circuited and the current \(I\) is measured. Which of the graphs shows the correct relationship between \(I\) and \(n?\)

1.		2.
3.		4.

Two cells having the same emf, are connected in series through an external resistance R. Cells have internal resistance r₁ and r₂ respectively. When the circuit is closed, the potential difference across the first cell is zero. The value of R is:

1. $r_1-r_2$

2. $\frac{r_1+r_2}{2}$

3. $\frac{r_1-r_2}{2}$

4. $r_1+r_2$

Two batteries, one of emf \(18\) volts and internal resistance \(2~\Omega\) and the other of emf \(12\) V and internal resistance \(1~\Omega,\) are connected as shown. The voltmeter \(\mathrm{V}\) will record a reading of: 

1. \(18\) V
2. \(30\) V
3. \(14\) V
4. \(15\) V