$A$ cell sends a current of $0.9\, A$ through a resistance of $2\, \Omega$ and a current of $0.3\, A$ through a resistance of $7\, \Omega$. The internal resistance of the cell is ............. $\Omega$.

In the given electrical circuit,the potential difference between points $P$ and $Q$ is ........... $V$.

Current $I$ is flowing through two materials having electrical conductivities $\sigma_1$ and $\sigma_2$ respectively $(\sigma_1 > \sigma_2)$ as shown in the figure. The total amount of charge at the junction of the materials is

In the circuit shown,the reading of the ammeter (ideal) is the same with both switches open as with both closed. Find the value of resistance $R$ in $\Omega$.

In terms of resistance $R$ and time $T$,the dimensions of the ratio $\frac{\mu}{\varepsilon}$ of the permeability $\mu$ and permittivity $\varepsilon$ is:

For the given circuit,the potential difference between $x$ and $y$ is ......... (in $V$)