Law of change Proportions: Assumptions, Explanation , step , reasons of Applicability and also Applicability the the legislation of change Proportions!

Law of change Proportions occupies an important place in financial theory. This legislation is additionally known as legislation of Proportionality.

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Keeping other factors fixed, the law defines the production role with one aspect variable. In the quick run as soon as output of a commodity is seek to it is in increased, the law of variable proportions comes into operation.

Therefore, when the number of one element is boosted or decreased, while other components are constant, the proportion in between the components is altered. Because that instance, there space two factors of production viz., land and labour.

Land is a fixed aspect whereas work is a variable factor. Now, suppose we have a land measuring 5 hectares. We prosper wheat top top it with the aid of variable aspect i.e., labour. Accordingly, the proportion in between land and also labour will be 1: 5. If the number of laborers is raised to 2, the brand-new proportion in between labour and land will certainly be 2: 5. early to readjust in the proportion of determinants there will likewise emerge a change in total output at various rates. This tendency in the concept of production referred to as the regulation of variable Proportion.


“As the ratio of the aspect in a mix of components is boosted after a point, first the marginal and then the typical product that that element will diminish.” Benham

“An increase in some inputs loved one to various other fixed inputs will in a provided state of modern technology cause output to increase, yet after a point the extra calculation resulting native the same enhancements of extra inputs will end up being less and less.” Samuelson


“The law of variable proportion says that if the entry of one resource is enhanced by same increment per unit the time while the entry of other resources are held constant, complete output will certainly increase, but past some allude the result output rises will become smaller and also smaller.” Leftwitch


Law of variable proportions is based upon following assumptions:

(i) consistent Technology:

The state of an innovation is suspect to be given and constant. If over there is an advancement in modern technology the production function will relocate upward.

(ii) variable Proportions room Variable:

The law assumes that factor proportions room variable. If components of manufacturing are come be an unified in a fixed proportion, the law has no validity.

(iii) Homogeneous variable Units:


The systems of variable variable are homogeneous. Every unit is the same in quality and amount through every other unit.

(iv) Short-Run:

The legislation operates in the short-run as soon as it is not possible to differ all variable inputs.

Explanation that the Law:

In order to know the regulation of variable proportions we take the instance of agriculture. Intend land and also labour room the only two determinants of production.

By keeping land together a resolved factor, the production of variable element i.e., labour have the right to be shown with the assist of the complying with table:


From the table 1 that is clear that there room three step of the regulation of variable proportion. In the very first stage typical production rises as there are more and more doses that labour and also capital employed with fixed factors (land). We view that full product, mean product, and marginal product increases yet average product and also marginal product increases up to 40 units. Later on, both begin decreasing because proportion of employees to land to be sufficient and land is not correctly used. This is the end of the first stage.

The second stage start from where the very first stage end or wherein AP=MP. In this stage, typical product and also marginal product begin falling. We have to note the marginal product drops at a much faster rate 보다 the median product. Here, complete product boosts at a diminishing rate. That is additionally maximum at 70 devices of labour where marginal product i do not care zero while mean product is never ever zero or negative.

The third stage starts where 2nd stage ends. This start from 8th unit. Here, marginal product is an adverse and full product falls yet average product is quiet positive. At this stage, any added dose leads to hopeful nuisance because extr dose leader to negative marginal product.

Graphic Presentation:

In fig. 1, ~ above OX axis, we have actually measured variety of labourers while amount of product is presented on OY axis. TP is total product curve. Up to point ‘E’, total product is enhancing at enhancing rate. Between points E and also G it is increasing at the to decrease rate. Below marginal product has started falling. At suggest ‘G’ i.e., when 7 units of labourers room employed, total product is preferably while, marginal product is zero. Thereafter, it starts to diminish equivalent to an unfavorable marginal product. In the lower component of the figure MP is marginal product curve.


Up to allude ‘H’ marginal product increases. At point ‘H’, i.e., as soon as 3 systems of labourers are employed, the is maximum. ~ that, marginal product begins to decrease. Before point ‘I’ marginal product becomes zero at suggest C and also it turns negative. AP curve represents mean product. Before suggest ‘I’, median product is much less than marginal product. At point ‘I’ average product is maximum. Up to suggest T, typical product increases but after that it starts to diminish.

Three stages of the Law:

1. An initial Stage:

First phase starts from point ‘O’ and also ends increase to point F. At suggest F mean product is maximum and is same to marginal product. In this stage, total product rises initially at increasing rate up to point E. Between ‘E’ and also ‘F’ it boosts at diminishing rate. Similarly marginal product also increases initially and reaches its maximum at point ‘H’. Later on, it begins to diminish and becomes equal to mean product at allude T. In this stage, marginal product exceeds average product (MP > AP).

2. 2nd Stage:

It begins from the point F. In this stage, total product boosts at diminishing rate and is in ~ its best at allude ‘G’ correspondingly marginal product diminishes rapidly and also becomes ‘zero’ at suggest ‘C’. Median product is best at allude ‘I’ and thereafter it begins to decrease. In this stage, marginal product is less than median product (MP 3. 3rd Stage:

This stage starts beyond allude ‘G’. Here complete product start diminishing. Typical product additionally declines. Marginal product turns negative. Law of diminishing returns firmly manifests itself. In this stage, no for sure will develop anything. This happens since marginal product the the work becomes negative. The employee will suffer losses through employing more units of labourers. However, that the 3 stages, a for sure will choose to create up to any given point in the second stage only.



In Which phase Rational Decision is Possible:

To make the things simple, allow us expect that, a is variable factor and also b is the resolved factor. And also a1, a2 , a3….are devices of a and also b1 b2b3…… are unit of b.

Stage i is characterized by boosting AP, so the the total product must additionally be increasing. This way that the efficiency of the variable factor of manufacturing is boosting i.e., output per unit that a is increasing. The performance of b, the resolved factor, is additionally increasing, since the total product through b1 is increasing.

The stage II is characterized by decreasing AP and a diminish MP, but with MP not negative. Thus, the performance of the variable variable is falling, if the effectiveness of b, the fixed factor, is increasing, due to the fact that the TP through b1 proceeds to increase.


Finally, stage III is characterized by falling AP and also MP, and also further by negative MP. Thus, the effectiveness of both the fixed and also variable aspect is decreasing.

Rational Decision:

Stage II becomes the relevant and also important stage of production. Production will no take location in either of the other two stages. It means production will not take location in stage III and also stage I. Thus, a rational producer will operate in stage II.

Suppose b to be a totally free resource; i.e., it commanded no price. An businessman would want to accomplish the biggest efficiency feasible from the aspect for which that is paying, i.e., from variable a. Thus, he would want to create where AP is maximum or at the boundary between stage I and also II.

If ~ above the various other hand, a were the cost-free resource, then he would want to employ b come its most efficient point; this is the boundary in between stage II and also III.

Obviously, if both resources commanded a price, the would create somewhere in phase II. In ~ what location in this stage manufacturing takes location would count upon the relative prices of a and also b.

Condition or reasons of Applicability:

There are many causes which room responsible because that the application of the legislation of variable proportions.


They room as follows:

1. Under utilization of resolved Factor:

In initial phase of production, fixed determinants of production like land or machine, is under-utilized. An ext units of change factor, prefer labour, are necessary for its proper utilization. As a an outcome of employment of additional units that variable determinants there is suitable utilization of addressed factor. In short, increasing returns come a factor begins to manifest itself in the first stage.

2. Fixed components of Production.

The foremost reason of the operation of this regulation is that some of the components of production are fixed throughout the quick period. As soon as the fixed variable is offered with change factor, climate its ratio compared to variable aspect falls. Production is the result of the co-operation of every factors. When second unit that a variable factor has to produce with the assist of reasonably fixed factor, then the marginal return of change factor starts to decline.

3. Optimum Production:

After make the optimum usage of a resolved factor, climate the marginal return of such variable factor begins to diminish. The an easy reason is that after the optimum use, the ratio of fixed and also variable factors end up being defective. Allow us intend a maker is a fixed factor of production. That is put to optimum use when 4 labourers are employed top top it. If 5 labourers are put on it, then total production increases very tiny and the marginal product diminishes.

4. Imperfect Substitutes:

Mrs. Joan Robinson has put the discussion that imperfect substitution of factors is greatly responsible because that the operation of the legislation of diminishing returns. One factor cannot be supplied in ar of the various other factor. After optimum use of addressed factors, variable components are increased and the quantity of fixed factor might be enhanced by its substitutes.

Such a substitution would rise the production in the exact same proportion together earlier. Yet in genuine practice determinants are imperfect substitutes. However, ~ the optimum use of a fixed factor, it can not be substituted by another factor.

Applicability the the regulation of change Proportions:

The law of variable proportions is universal as it applies to all fields of production. This law applies to any field of manufacturing where some determinants are fixed and also others space variable. The is why the is referred to as the law of universal application.

The main reason of applications of this regulation is the fixity of any kind of one factor. Land, mines, fisheries, and house building etc. Are not the only instances of solved factors. Machines, raw materials may additionally become fixed in the short period. Therefore, this legislation holds an excellent in all tasks of production etc. Agriculture, mining, manufacturing industries.

1. Applications to Agriculture:

With a view of raising farming production, labour and also capital can be boosted to any type of extent but not the land, being fixed factor. For this reason when much more and an ext units of variable components like labour and also capital are used to a fixed factor then their marginal product starts come diminish and also this legislation becomes operative.

2. Application to Industries:

In order to rise production of made goods, determinants of production needs to be increased. It have the right to be enhanced as preferred for a long period, gift variable factors. Thus, legislation of boosting returns operates in industries for a long period. But, this situation arises when additional units the labour, capital and enterprise are of inferior high quality or are easily accessible at greater cost.

As a result, after ~ a point, marginal product boosts less proportionately than increase in the units of labour and capital. In this way, the regulation is equally precious in industries.

Postponement the the Law:

The postponement that the law of change proportions is feasible under adhering to conditions:

(i) improvement in technique of Production:

The procedure of the law have the right to be postponed in case variable determinants techniques of production are improved.

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(ii) Perfect Substitute:

The legislation of change proportion can additionally be postponed in situation factors of manufacturing are made perfect substitutes i.e., as soon as one element can be substituted because that the other.


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