Answer in detail
1) Explain the law of supply and its exceptions.
Answer: – The law of supply is also a fundamental principle of economic theory like the law of demand. It was introduced by Prof. Alfred Marshall in his book, ‘Principles of Economics’ which was published in 1890. The law explains the functional relationship between price and quantity supplied.
Statement of the Law:
“Other things being constant, higher the price of a commodity, more is the quantity supplied and lower the price of a commodity less is the quantity supplied”.
In simple words, “other factors remain constant, a rise in price results in a rise in the quantity supplied and vice-versa. Thus, there is a direct relationship between price and quantity supplied.
Sx = f (Px)
S = Supply
x = Commodity
f = Function
P = Price of commodity
Law of supply is explained with the help of the following schedule and diagram:
Price of commodity x (in ₹)
Supply of commodity x (in kgs.)
In the above table explains the direct relationship between price and quantity of commodity supplied.
When price rises from ₹ 10 to 20, 30, 40 and 50, the supply also rises from 100 to 200, 300, 400 and 500 units respectively.
Thus, there is a direct relationship between price and quantity supplied which is shown in following figure:
In the above figure, X-axis represents quantity supplied and Y-axis represents the price of the commodity. Supply curve ‘SS’ slopes upwards from left to right which has a positive slope. It indicates a direct relationship between price and quantity supplied.
Exceptions to the Law of Supply:
Following are the exceptions to the law of supply:
1) Supply of labour:
Labour supply is the total number of hours that workers work at a given wage rate. It is represented graphically by a supply curve. In the case of labour, as the wage rate rises the supply of labour (hours of work) would increase. So the supply curve slopes upward. Supply of labour (hours of work) falls with a further rise in wage rate and supply curve of labour bends backward. This is because the worker would prefer leisure to work after receiving a higher amount of wages. Thus, after a certain point when the wage rate rises the supply of labour tends to fall.
It can be explained with the help of a backward bending supply curve. The following table and diagram explain the backward bending supply curve of labour.
wage rate (₹) per hour
Hours of work per day
Total amount of wages (₹)
In the above figure, the supply of labour (hours of work) is shown on X-axis and wage rate per hour is shown on the Y-axis. The curve SAS represents the backward bending supply curve of labour. Initially, when the wage rate is ₹ 100 per hour, the hours of work are 5. The total amount of wages received is ₹ 500. When the wage rate rises from ₹ 100 to ₹ 200, hours of work will also rise from 5 hours to 7 hours and the total amount of wages would also rise from ₹ 500 to ₹ 1400. At this point, labourers enjoy the highest amount i.e. ₹ 1400 and work for 7 hours. If the wage rate rises further from ₹ 200 to ₹ 300, the total amount of wages may rise, but the labourer will prefer leisure time and denies working for extra hours. Thus, he is ready to work only for 6 hours. At point A, the supply curve bends backward, which becomes an exception to the law of supply.
2) Agricultural goods: The law of supply does not apply to agricultural goods as they are produced in a specific season and their production depends on weather conditions. Due to unfavourable changes in weather, if the agricultural production is low, their supply cannot be increased even at a higher price.
3) Urgent need for cash: If the seller is in urgent need for hard cash, he may sell his product at which may even be below the market price.
4) Perishable goods: In case of perishable goods, the supplier would offer to sell more quantities at lower prices to avoid losses. For example, vegetables, eggs etc.
5) Rare goods: The supply of rare goods can not be increased or decreased according to its demand. Even if the price rises, supply remains unchanged. For example, rare paintings, old coins, antique goods etc.