Compare changes in the equilibrium price and quantity when demand increases in a market with an upward sloping supply curve and in a market with a vertical supply curve.

When a market has an upward sloping supply curve, an increase in demand will cause both the equilibrium price and the equilibrium quantity to rise. When a market has a vertical supply curve, an increase in demand will cause only the equilibrium price to rise; the equilibrium quantity remains the same because the quantity supplied is fixed and cannot adjust.