2. Second-degree price discrimination. In this situation a firm may charge different prices for different levels of consumption. The first Q1 units may be sold at the high price of P1; the next block of units, Q2 = Q1, may be sold at the price P2, and the last block of units, Q3=Q2,may be sold at the price of P3. This situation is also shown in Figure 10.2 and the size of the consumer surplus is
given by the three triangles, GAP1, ABE and BCF. This type of strategy may be used in the selling of a product like electricity.