5. Short-run supply and long-run equilibrium Considet the Derfectiv competitive market for copper. Assume that, regardless of how many firms are in the industry, every firm in the industry is identical and faces the marginal cost (MC), average total cost (ATC), and average wariable cost (AV) curves shown on the following graph. This follewing diagram stiowe the market demand for copper. If there Mere 20 firms in this market, the short-run equilitium price of conperi would be per pound. At that price, firms in this industry would Therefore, in the long run, firms would. the copper market. Because you know that perfectly cornpetitive firms earn Gcanomic profit in the long run, you know the long-run equilibrium price must be per pound. From the graph, you cari see that this means there will he firms operating in the copper industry in longrun equilibrium