What is the commercial unit of electric energy?

Power of a lamp is $60\, W$. Find the energy in joules consumed by it in $1\, s$. (in $, J$)

What happens to the resistance of a conductor when the length of the conductor is reduced to half?

Why should the melting point of a fuse wire be low?

Two wires $A$ and $B$ are of the same metal,have the same area of cross-section,and have their lengths in the ratio $2:1$. What will be the ratio of currents flowing through them respectively,when the same potential difference is applied across each of them?

When an electric iron is connected to a $220\;V$ line and a current of $5\;A$ flows through it,what is the power of the iron?