However, things other than price affect how much of a good or service people are willing to supply. These other determinants of supply are prices of resources, technology and productivity, expectations or producers, the number of producers, and the prices of related goods or services. When one of these determinants of supply changes, the whole supply schedule changes. A picture of a supply schedule is called a supply curve . Again price is put on the vertical axis and quantity on the horizontal axis.
Supply curves slope up from left to right.
When one of the determinants of supply changes, the supply curve shifts to the left or the right. The price of a good or service changes until the equilibrium price is reached. Equilibrium is the point at which the quantity demanded equals the quantity supplied at a particular price. At prices above the equilibrium price, the quantity supplied is greater than the quantity demanded, so a surplus develops. Sellers must lower their prices to get rid of the goods and services that accumulate.