These Determination of Income and Employment Class 12 Notes explain how equilibrium income and employment are determined in an economy through aggregate demand and aggregate supply. The chapter discusses consumption function, investment function, multiplier mechanism, effective demand and paradox of thrift based on Keynesian theory.
These NCERT notes are prepared for quick revision and competitive exam preparation, covering important formulas, graphical concepts, multiplier analysis and equilibrium determination useful for CBSE board exams, CUET and other commerce examinations.
Determination of Income and Employment explains how national income and employment are determined in the short run under the assumptions of fixed prices and constant interest rate. The chapter is based on the Keynesian theory of aggregate demand and effective demand.
The chapter further discusses consumption function, investment demand, equilibrium output, multiplier process and paradox of thrift. It also explains how changes in autonomous expenditure influence equilibrium income.
These NCERT Notes on Determination of Income and Employment explain the concepts of aggregate demand, planned expenditure and equilibrium income in a two-sector economy.
Aggregate demand refers to planned expenditure on final goods and services in an economy.
These notes explain the relationship between consumption and income through the Keynesian consumption function.
C = C̄ + cY
Where:
Consumption that occurs even when income is zero.
Consumption that changes with income.
MPC = ΔC / ΔY
S = Y – C
Where:
MPS = ΔS / ΔY
MPC + MPS = 1
APC = C / Y
APS = S / Y
These notes explain the meaning and assumptions of investment expenditure in the Keynesian model.
Investment means addition to:
I = Ī
Investment is assumed autonomous and independent of income.
These NCERT notes explain equilibrium income determination in an economy consisting of households and firms.
AD = C + I
Substituting consumption function:
AD = C̄ + Ī + cY
Y = AD
or
Y = C̄ + Ī + cY
A = C̄ + Ī
Y = A / (1-c)
These notes explain equilibrium determination under fixed price assumptions using graphical and algebraic methods.
AD = C̄ + Ī + cY
Aggregate supply is represented by a 45° line because:
Y = AD
Y = (C̄ + Ī) / (1-c)
These notes explain how equilibrium income changes due to changes in autonomous expenditure.
Increase in autonomous expenditure shifts AD upward.
These NCERT notes explain how a small increase in investment leads to a larger increase in equilibrium income.
Multiplier = ΔY / ΔA = 1 / (1-c)
Where:
If:
Multiplier = 1 / (1-0.8) = 5
₹10 increase in investment increases income by ₹50.
These notes explain the Keynesian paradox where increased savings may not increase total savings in the economy.
Higher thriftiness can reduce national income.
Aggregate demand < Full employment output
Aggregate demand > Full employment output
These notes explain the Keynesian principle that equilibrium output depends on aggregate demand.
Aggregate output is determined by aggregate demand under fixed prices.
Higher autonomous expenditure increases equilibrium output through multiplier process.
| Important Topic | Page Reference |
|---|---|
| Aggregate Demand | Pages 53–54 |
| Consumption Function | Pages 54–55 |
| Investment Function | Page 56 |
| Equilibrium Income | Pages 57–60 |
| Multiplier Mechanism | Pages 61–62 |
| Paradox of Thrift | Pages 63–64 |
| Effective Demand | Page 65 |
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Aggregate demand is the planned expenditure on final goods and services in an economy.
Marginal Propensity to Consume measures change in consumption due to change in income.
Equilibrium occurs when aggregate demand equals aggregate supply.
Investment multiplier shows the ratio of change in income to change in investment.
It explains that higher savings may reduce aggregate demand and national income.