It takes $15 \ min$ to heat water in an electric kettle. If the length of the heating coil is reduced to $2/3$ of its original length,how many minutes will it take to heat the same amount of water?

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

In the following circuit diagram,$E = 4\,V, r = 1\,\Omega$ and $R = 45\, \Omega$,then the reading of the ammeter $A$ will be

$A$ battery of $e.m.f.$ $10\, V$ is connected to a resistance network as shown in the figure. The potential difference ${V_A} - {V_B}$ between the points $A$ and $B$ is .................... $V$.

In the following circuit,$1 \,\Omega$ resistor dissipates power $P$. If the resistor is replaced by $9 \,\Omega$,the power dissipated in it is

$A$ $16 \ \Omega$ wire is bent to form a square loop. $A$ $9 \ V$ battery with internal resistance $1 \ \Omega$ is connected across one of its sides. If a $4 \ \mu F$ capacitor is connected across one of its diagonals,the energy stored by the capacitor will be $\frac{x}{2} \ \mu J$,where $x = . . . . . . .$