When the slope of a demand curve is constant, price elasticity of demand can vary.

Constant Slope

The unchanging steepness or incline of a line on a graph, indicating a steady rate of change between two variables.

Price Elasticity

A measure of how much the quantity demanded of a good responds to a change in the price of that good, demonstrating the sensitivity of consumers to price changes.

Demand Curve

A demand curve is a graph showing the relationship between the price of a good and the quantity of that good that consumers are willing and able to purchase at various prices.