In which market models are firm's demand curves different from their marginal revenue curves?

Question

Quizplus · Accepted Answer

In monopolistic competition, the firm's demand curve is downward sloping and elastic, as there are close substitutes available, whereas the marginal revenue curve will lie below the demand curve, and will be steeper because of the downward-sloping demand curve. In a monopoly, the firm faces the entire market demand curve, which is downward-sloping and elastic, and the marginal revenue curve lies below the demand curve and is twice as steep. In an oligopoly, the firm's demand curve depends on the actions of other firms in the industry, but the marginal revenue curve will still be below the demand curve, and may be steeper. Therefore, in monopolistic competition, monopoly, and oligopoly, the firm's demand curves differ from their marginal revenue curves.

In Which Market Models Are Firm's Demand Curves Different from Their