1 When the price elasticity of demand for a good is unit (or unitary) elastic (E d = 1), the percentage change in quantity is equal to that in price, so a change in price will not affect total revenue.2  When the price elasticity of demand for a good is relatively elastic d. When the price elasticity of demand for a good is relatively elastic d. 2  When the price elasticity of demand for a good is perfectly elastic (E d is − ∞), any increase in the price, no matter how small, will cause demand for the good to drop to zero. 3  Hence, when the price is raised, the total revenue falls to zero.