What is the practical unit used for electrical energy?

State a difference between the wire used in the element of an electric heater and in a fuse wire.

An electric bulb is rated $220\, V$ and $100\, W$. When it is operated on $110\, V$,the power consumed will be ....... $W$.

Compute the heat generated while transferring $96000$ coulomb of charge in one hour through a potential difference of $50\, V$.

$(a)$ Why is the series arrangement not used for domestic circuits?
$(b)$ Why is tungsten used almost exclusively for the filament of electric lamps?
$(c)$ Why are the conductors of electric heating devices,such as bread toasters and electric irons,made of an alloy rather than a pure metal?
$(d)$ Why are copper and aluminium wires usually employed for electricity transmission?
$(e)$ Why does the cord of an electric heater not glow while the heating element does?

Define electric power. Give its $SI$ unit.