Resistance

Things to remember

• The resistance of a conductor can be defined as the property of the conductor that opposes the flow of electric current through it. 
• The resistance of a conductor is directly proportional to its length.
•  The resistance of a conductor increases with increase in temperature.
• The resistivity of a material is numerically equal to the resistance of a conductor of unit area per unit length of a material.
• The reciprocal of the resistivity (ρ) of a material is called its conductivity (σ) sigma.