If power in external resistance $R$ is maximum then

$(i) R = r$                              $(ii)$ Power in $R$ is $\frac{{{E^2}}}{{4R}}$

$(iii)$ Input power $\frac{{{E^2}}}{{2R}}$         $(iv)$Efficiency is $50\%$

$4$ bulbs marked $40\, W$, $250\, V$ are connected in series with $250\, V$ mains. The total power is ............. $W$

Some electric bulbs are connected in series across a $220\, V$ supply in a room. If one bulb is fused then remaining bulbs are connected again in series across the same supply. The illumination in the room will

Two wires $A$ and $B$ of same material and mass have their lengths in the ratio $1 : 2$. On connecting them to the same source, the rate of heat dissipation in $B$ is found to be $5\,W$. The rate of heat dissipation in $A$ is............ $W$

Two wires with resistances $R$ and $2R$ are connected in parallel, the ratio of heat generated in $2R$ and $R$ is

The capacitor shown in fig. is in steady state. The energy stored in the capacitor is