Which cell is generally used in the hearing aids? Name the material of the anode, cathode and the electrolyte. Write the reactions involved.

In case two cells are identical, each of emf $E=5 \mathrm{V}$ and internal resistance $r=2 \Omega$, calculate the voltage across the external resistance $R=10 \Omega$

The circuit diagram of a potentiometer for determining the $\mathrm{emf} \text{'}\mathrm{E}\text{'}$ of a cell of negligible internal resistance is as shown in figure:

Derive an expression to find out internal resistance of a cell.

Two cells of emf $2E$ and $E$ with internal resistance $r_1$and $r_2$ respectively are connected in series to an external resistor $R$ (see figure). The value of $R,$ at which the potential difference across the terminals of the first cell becomes zero is

In the network shown, the equivalent resistance between $\mathrm{A}$ and $\mathrm{B}$ is $\frac{4}{3}\mathrm{\Omega }$, find the value of $\mathrm{r}$.

The figure shows a part of a closed circuit. If the current flowing through it is $2 \mathrm{A}$ then $V_B-V_A$ is _______

The variation of terminal potential difference $\left(V\right)$ with current flowing through as cell is as shown

The $\mathrm{emf}$ and internal resistance of the cell are