Water fall from a $40\,m$ high dam at the rate of $9 \times 10^{4}\,kg$ per $hour$. Fifty percentage of gravitational potential energy can be converted into electrical energy. Using this hydroelectric energy number of $100\,W$ lamps, that can be lit, is

(Take $\left.g=10\,ms ^{-2}\right)$

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

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 uniform metallic wire of length $L$ is mounted in two configurations. In configuration $1$ (triangle), it is an equilateral triangle and a voltage $V$ is applied to corners $A$ and $B$. In configuration $2$ (circle), it is bent in the form of a circle and the potential $V$ is applied at diametrically opposite points $P$ and $Q$. The ratio of the power dissipated in configuration $1$ to configuration $2$ is

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

If resistance of the filament increases with temperature, what will be power dissipated in a $220\, V- 100\, W$ lamp when connected to $110\, V$ power supply