What is the value of $1 \, kWh$ in Joules?

$A$ bulb rated $100\, W, 220\, V$ is connected to a $110\, V$ supply. What is the power consumed in $W$?

$A$ $220\, V$,$1000\, W$ bulb is connected across a $110\, V$ mains supply. The power consumed will be ............ $W$.

$A$ light bulb operates at a voltage $V_0$ and consumes power $P_0$. If the voltage is changed to $V$,what is the new power $P$ consumed by the bulb?

$A$ hot electric iron has a resistance of $80\,\Omega$ and is used on a $200\,V$ source. The electrical energy spent,if it is used for two hours,will be ........... $Wh$.

An electrical cable having a resistance of $0.2 \Omega$ delivers $10 \text{ kW}$ at $200 \text{ V}$ $D$.$C$. to a factory. What is the efficiency of transmission (in $\%$)?