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1、完全竞争市场上的厂商均衡,7.2 The Equilibrium of the Firm under Perfect Competition,教学目标Objectives：了解完全竞争的市场条件掌握完全竞争市场的需求曲线和收益曲线掌握完全竞争市场的短期均衡条件掌握完全竞争市场的长期均衡条件知识点Knowledge：完全竞争的市场条件、完全竞争市场的需求曲线和收益曲线完全竞争市场的短期均衡和长期均衡条件技能点Skills：绘制完全竞争市场均衡图,price taker advertising market opportunities ideal type advantages shortcomi
2、ngs government Normal profit Supernormal profit least-cost economic profit abnormal profit homogeneous product economies of scale industry,专业词汇Professional terms,一、完全竞争的含义与条件,Assumptionsl Firms are price taker.l There is complete freedom of entry into the industry for new firms.l All firms produce a
3、n identical product.The product is homogeneous,so there is no branding and advertising.l Producers and consumers have perfect knowledge of the market.That is,producers are fully aware of prices,costs and market opportunities.Consumers are fully aware of the price,quantity and availability of the pro
4、duct.,Nevertheless,despite the lack of real-world cases,the model of perfect competition plays a very important role in economic analysis and policy.Its major relevance is as an ideal type.Many on the political right argue that perfect competition brings a number of important advantages.The model ca
5、n thus be used as a standard against which to judge the shortcomings of real world industries.It can help government to formulate policies towards industry.,一、完全竞争的含义与条件,实现完全竞争的条件包括：第一，市场上有许多生产者与消费者，每一个生产者的销售量与消费者的购买量只占市场极小的份额。第二，市场上的产品是同质的，即不存在产品差别。第三，资源完全自由流动。第四，市场信息是畅通的。,一、完全竞争的含义与条件,The short ru
6、n and the long run lThe short run under perfect competition The period during which there is too little time for new firms to enter the industry.l The long run under perfect competition The period of time that is long enough for new firms to enter the industry.Normal profit The opportunity cost of b
7、eing in business:the profit that could have been earned in the next best alternative business.It is counted as a cost of production.Supernormal profit(also known as pure profit,economic profit,abnormal profit or simply profit)The excess of total profit above normal profit.,二、完全竞争市场上的需求和收益曲线,三、完全竞争市场
8、上的短期均衡,三、完全竞争市场上的短期均衡,厂商获得正常利润(normal profit),三、完全竞争市场上的短期均衡,厂商获得超额利润(supernormal profit),三、完全竞争市场上的短期均衡,厂商遭受亏损,三、完全竞争市场上的短期均衡,四、完全竞争市场上的长期均衡,五、对完全竞争市场的评论,In many industries,firms may have to be quite large if they are to experience the full potential economies of scale.But perfect competition requi
9、res there to be many firms.Firms must therefore be small in most for economies of scale.Once a firm expands sufficiently to achieve economies of scale,it will usually gain market power.It will be able to undercut the prices of smaller firms,which will thus be driven out of business.Perfect competiti
10、on is destroyed.Perfect competition could only exist in any industry,therefore,if there were no(or virtually no)economies of scale.,Perfect competition and the public interest,There are a number of features of perfect competition which,it could be argued,benefit society:l Price equals marginal cost,
11、which has important implications for the allocation of resources between alternative products.l If a firm becomes less efficient than other firms,it will make less than normal profits and be driven out of business.If it is more efficient,it will earn supernormal profits.Thus the competition between
12、firms will act as a spur to efficiency.l Similarly,the desire for supernormal profit,and the desire to avoid loss,will encourage the development of new technology.,Perfect competition and the public interest,lThere is no point in advertising under perfect competition,since all firms produce a homoge
13、neous product.This and the previous two factors will lead to low AC curves,and hence to an economical use of the nations scarce resources.lFor any given technology,the firm,in the long run,will produce at the least-cost output.l The consumer gains from low prices,since not only are costs kept low,bu
14、t also there are no long-run supernormal profits to these costs.lIf consumer tastes change,the resulting price change,the resulting price change will lead firms to respond(purely out of self-interest).An increased consumer demand will call forth extra supply with only a short-run increase in profit.
15、,五、对完全竞争市场的评论,第一，社会供给与需求相等，使资源得到最优配置，生产者的生产不会有不足或过剩，消费者的需求也得到了充分满足。第二，在长期均衡时所达到的平均成本处于最低点，表明可以通过完全竞争与资源的自由流动，使生产要素的效率得到最有效的发挥。第三，平均成本最低决定了产品的价格也是最低的，这对消费者是有利的。,益处：,五、对完全竞争市场的评论,第一，各厂商的平均成本最低并不一定是社会成本最低。第二，产品无差别，这样，消费者的多种需求无法得到满足。第三，完全竞争市场上生产者的规模都很小，这样，他们没有能力去实现重大的科学技术突破，从而不利于科学技术发展和科技创新。第四，在实际经济生活中，完全竞争的情况是很少的，而且，一般来说，竞争也必然引起垄断。,弊端：,
