ABSTRACT
This chapter explains resistance variation due to length, cross-sectional area, type of material and temperature variation. The resistance to the flow of charge in an electric circuit is analogous to the frictional effects between water and the pipe surfaces as well as the resistance offered by obstacles that are present in its path. The value of a resistor also changes with changing temperature, but this is not, as people might expect, mainly due to a change in the dimensions of the component as it expands or contracts. Resistance R is directly proportional to length l of a conductor. It is inversely proportional to cross-sectional area of a conductor. The temperature coefficient of resistance of a material is the increase in the resistance of a 1 resistor of that material when it is subjected to a rise of temperature of 1C. The constant of proportionality is known as the resistivity of the material.
