Figure shows three resistor configurations $R_1,R_2$ and $R_3$ connected to $3\,V$ battery. If the power dissipated by the configuration $R_1, R_2$ and $R_3$ is $P_1, P_2$ and $P_3$ , respectively then

It takes $12$ minutes to boil $1$ litre of water in an electric kettle. Due to some defect it becomes necessary to remove $20 \%$ turns of heating coil of the kettle. After repair, how much time will it take to boil $1$ litre of water.

A cell of $e.m.f.$ $1.5\,V$ having a finite internal resistance is connected to a load resistance of $2\,\Omega $. For maximum power transfer the internal resistance of the cell should be ............. $ohm$

A torch bulb rated as $4.5\, W, 1.5\, V$ is connected as shown in the figure. The $e.m.f.$ of the cell needed to make the bulb glow at full intensity is ............. $V$

Ametallic conductor of irregular cross-section is as shown in the figure. Aconstant potential difference is applied across the ends $(1)$ and $(2)$. Then :

In a building there are $15$ bulbs of $45\; \mathrm{W}, 15$ bulbs of $100\; \mathrm{W}, 15$ small fans of $10 \;\mathrm{W}$ and $2$ heaters of $1 \;\mathrm{kW}$. The voltage of electric main is $220\; \mathrm{V}$. The minimum fuse capacity (rated value) of the building will be: .......... $A$