Q. What do you mean by Resistance?

An ideal resistor is a circuit element with the property that the current through it is linearly proportional to the potential difference across its terminals,

i = v/R = Gv, or v = iR

which is known as Ohm's law, published in 1827. R is known as the resistance of the resistor with the SI unit of ohms (), and G is the reciprocal of resistance called conductance, with the SI unit of siemens (S). The circuit symbols of ?xed and variable resistors along with an illustration of Ohm's law. Most resistors used in practice are good approximations to linear resistors for large ranges of current, and their i-v characteristic (current versus voltage plot) is a straight line.