IBonomicsEngel Curve (Normal and Inferior Goods)SL
MicroeconomicsThe Engel Curve illustrates how the quantity demanded of a good changes as consumer income changes, distinguishing between normal and inferior goods.
Curves and elements
- engel curve
- Engel Curve: Illustrates how the quantity demanded of a good changes in response to changes in consumer income.
- normal goods
- Normal Goods: Demand increases with rising income. Represented by the upward-sloping section of the curve.
- inferior goods
- Inferior Goods: Demand decreases with rising income. Represented by the downward-sloping section of the curve.
Key explanations
- 1
The curve shows the relationship between a consumer's income and the quantity of a good they purchase.
- 2
For normal goods, as income increases, quantity demanded also increases — shown by the upward-sloping section of the curve below income level 30.
- 3
For inferior goods, quantity demanded decreases as income increases — seen in the downward-sloping section above income level 30.
- 4
Goods may switch from being normal to inferior at a certain income threshold, depending on consumer preferences.
- 5
Understanding Engel curves helps policymakers and businesses predict changes in demand as income levels shift across the economy.
Example exam question
Using an Engel Curve, explain the difference between normal goods and inferior goods with reference to changes in consumer income.
Show example answer
The Engel Curve shows how demand for a good changes with income. For normal goods, demand increases as income rises — examples include fresh vegetables, smartphones, or gym memberships. For inferior goods, demand decreases as income rises — examples include instant noodles or second-hand clothes. The turning point on the curve represents an income level at which the good switches from normal to inferior. This distinction helps explain consumer behavior and guides firms in targeting different market segments.
