When an electric heater is switched on, the current flowing through it $(I)$ is plotted against time $(t)$. Taking into account the variation of resistance with temperature, which of the following best represents the resulting curve?

In the given circuit,the reading of the voltmeter connected across the $400\,\Omega$ resistor is $30\,V$. If it is connected across the $300\,\Omega$ resistor,what will be its reading in $V$?

The figure shows a tetrahedron,each side of which has a resistance $r$. Choose the correct diagram$(s)$,which show a two-dimensional equivalent of the tetrahedron.

In the circuit shown in the figure,the $5\,\Omega$ resistance develops $20.00\,cal/s$ due to the current flowing through it. The heat developed in the $2\,\Omega$ resistance (in $cal/s$) is

For what value of the resistor $X$ will the equivalent resistance of the two circuits shown be the same?

$A$ battery of $emf$ $E$ and internal resistance $r$ is connected across a resistance $R$. Resistance $R$ can be adjusted to any value greater than or equal to zero. $A$ graph is plotted between the current $(i)$ passing through the resistance and potential difference $(V)$ across it. Select the correct alternative$(s)$.