long-run effects - elasticities can change in the long run  

• elasticity - generally the slope of the curves
  • will alter the shape of the triangles and areas between the curves and market clearing price
• change elasticity >> change relative amount of surplus
• demand and supply have same elasticities >> tax split evenly between consumers and producers
  • demand grows more elastic >> demand curve gets flatter >> less of tax falls on consumer
  • demand grows more inelastic >> demand curve gets steeper >> more of tax falls on consumer
  • same applies for supply curve

• fraction of tax paid by consumer
• fraction of tax paid by producer

• demand curve gets more elastic
• notice that the equilibrium stays at the same point and tax (p_b - p_s) remains the same
• everything merely shifts
• fraction of tax paid by consumer now exceeds fraction of tax paid by producer