Question

When the firms will leave the market in long run perfectly competitive?

Answer 1

The process of firms leaving Industry B and entering A will continue until firms in both industries are earning zero economic profit. That suggests an important long-run result: Economic profits in a system of perfectly competitive markets will, in the long run, be driven to zero in all industries. Why do firms in perfect competition earn normal profit in the long run. In the long run, all factors of production are variable. ... Firms will exit until the remaining ones make normal profit again. So in the long run, all firms in perfect competition earn normal profit (or zero economic profit).