Production and Costs – Class 12 Economics Chapter 3 Notes & NCERT PDF

Introduction

Chapter 3 turns from the consumer to the producer. Production is the process by which inputs (labour, machines, land, raw materials) are transformed into output. A firm pays for inputs (its cost), sells output (its revenue) and aims to earn the maximum profit = revenue − cost. To find the profit-maximising output (Chapter 4), we first need the relationship between inputs and output (the production function) and then the firm's cost structure. The book assumes production is instantaneous and uses production and supply interchangeably.

Key Concepts

3.1 Production Function

The production function gives the maximum output that can be produced from each combination of inputs, for a given technology: q = f(L, K). The book's farmer example is q = K × L; with 1 hectare and 2 hours of labour the farmer gets 2 tonnes of wheat. Because it gives the maximum output, the production function deals only with efficient use of inputs. If technology improves, we get a new production function.

Table 3.1 gives output for labour 0 to 6 and capital 0 to 6. With 1L and 1K output is 1; with 2L and 2K it is 10; with 3L and 2K it is 18. If either input is zero, output is zero.

Isoquant: the set of all input combinations that give the same maximum output. In Table 3.1, output 10 comes from (4L, 1K), (2L, 2K) and (1L, 4K). Isoquants slope downward when marginal products are positive.

3.2 Short Run and Long Run

These periods are defined by whether all inputs can be varied, not by days or months.

3.3 Total, Average and Marginal Product

Keeping capital fixed at 4 units (Table 3.2):

TP is the sum of all marginal products, and AP is the average of the marginal products up to that level. MP is undefined at zero input.

3.4 Law of Diminishing Marginal Product / Law of Variable Proportions

When one factor is fixed and the other is increased, MP of the variable factor first rises and then falls. The reason is changing factor proportions: at first, more workers make better use of the fixed land; beyond a point, the land becomes "crowded" and each extra worker adds less. In Table 3.2, MP rises up to 3 units of labour (10, 14, 16) and then falls (10, 6, 1).

3.5 Shapes of TP, MP and AP Curves

3.6 Returns to Scale (long run)

If all inputs are increased t times:

For the Cobb-Douglas function q = x1^α x2^β, scaling inputs by t gives t^(α+β) times the output: CRS if α + β = 1, IRS if α + β > 1, DRS if α + β < 1.

3.7 Costs

The cost function gives the least cost of producing each level of output, given input prices and technology. (For example, output 50 can be produced by (6L, 3K), (4L, 4K) or (3L, 6K); the firm chooses the cheapest.)

Short run costs (Table 3.3, TFC = ₹20):

Shapes:

Long run costs: all costs are variable, so there is no fixed cost. LRAC = TC/q, LRMC = (TC at q1) − (TC at q1 − 1). LRAC is U-shaped: the falling part reflects IRS, the minimum point CRS and the rising part DRS. LRMC is also U-shaped and cuts LRAC from below at its minimum.

Worked Numericals

Formula Sheet

Board Exam Focus

Key Terms

Common Mistakes