The long run supply curve will tend to reflect the behaviour of production costs as an industry expands when more firms enter the industry. An increasing cost industry has an upward sloping supply curve.This is based on the assumption that as new firms enter, factor prices are bid up through the competition of more firms for the limited factor services.

Could you please describe why the long run supply curve can be downward sloping and the implication for the behavious of price as demand increases over the long run. Please illustrate this with graph.