# The laws of resistance

In law of resistance length, cross section area resistively is the main term of this law.

There are two basic laws of resistance. The resistance formula is

**(i)Law of length:** The resistance of a conductor is proportional to its length when the temperature, cross section area and its material is fixed.

If the resistance wire is R and the length is L.

Then mathematically

A long wire resistance is more and short wire resistance is less when the both wire is made of same material and same cross section.

**(ii) Law of cross section area:** The resistance is inversely proportional to its cross section area when the length, temperature and material remain fixed.

If the resistivity of conductor is R and the cross section area is A.

Mathematically

That means when the length and material of a conductor is fixed, resistance of a thin wire is more and it is less for thick wire.