Price affects quantity demanded or quantity supplied, but not demand or supply. This is because price is a determinant of quantity demanded or supplied, but not a determinant of the entire demand or supply curve. Changes in price lead to movements along the demand or supply curve, resulting in changes in quantity demanded or supplied. On the other hand, factors such as income, tastes and preferences, population, and expectations determine the entire demand or supply curve.
In monopolistic competition, price is determined based on the level of competition and product differentiation. Firms in this market structure have some control over the price they charge due to product differentiation. They can set prices based on factors such as production costs, desired profit margins, and the perceived value of their product in the market.
In an oligopoly, price determination is influenced by the behavior of a few dominant firms in the market. These firms have significant market power and can engage in strategic pricing decisions. Price is often determined through collusion or tacit agreements among the dominant firms. Factors such as market share, production costs, and competitive strategies play a crucial role in price determination in an oligopoly.