perfect competition

beware diagram in above video not correct... shows long run equilibrium in momopolistic competition... if perfect the AR curve would be perfectly elastic for the firm

video tutor:
perfect competition video (holden)

revenue curves perfect v imperfect (Holden)

flash based diagrams:
http://www.flashecon.org/profitA/profitA_main.asp - perfect competition

http://www.flashecon.org/profitB/profitB_main.asp - imperfect competition

video case study:  daffodil farmers