Price elasticity of demand is the degree of responsiveness of the quantity demanded of a good to a change in its price. Following are the factors affecting price elasticity of demand There are five degrees of price elasticity of demand which are gIven as:
(i) Perfectly Elastic Demand (e_D = \(\infty \)). When the demand of a commodity rises or falls to any extent at the prevailing price, it is said to be perfectly elastic demand. Here coefficient of elasticity of demand =\(\infty\) (infinity). See Fig. (a).

(ii) PerfectlyInelastic Demand (eD =0).When the demand of a commodity does not change at all irrespective of any change in its price, it is said to be perfectly inelastic demand. Here coefficient of elasticity of demand = 0 (zero). See Fig. (b).

(iii) UnitEkisticDemand(eD =1).When percentage change in the demand of a commodity is equal to the percentage change in its price, it is said to be unit elastic demand. Here coefficient of elasticity of demand = 1. See Fig.(c).

(iv)More Elastic Demand (eD > 1). When percentage change in demand of a commodity is more than the percentage change in its price, it is called greater than unitary elastic demand. Here coefficient of elasticity of demand> 1. See Fig. (d)

(v) Less than Unitary Elastic Demand (eD < 1). When percentage change in demand of a commodity is less than the percentage change in its price, it is called less than unitary elastic demand or less elastic demand. Here coefficient of elasticity of demand < 1. See Fig. (e).