 The marginal physical productivity is the rate of change in the total production with respect to one input or the last unit of the input. And this law of diminishing marginal productivity, it tells us that when we are going to utilize more and more number of one input gradually there will be a point that after this, this one additional unit of input, it will not add in the total output rather it may cause that decline in the total output. Or other words we can say that when we use one input, we see that our total production is increasing with 2 units, 3 units, 4 units. And even if we are going to add one more and more and more, then what will happen that the total production will decline. Now if we look at this aspect that law of diminishing marginal productivity tells us actually a sense of what it tells us. So don't look at attached resources with this aspect. Means if we are going to enhance more and more number of input, it can also be labor, it can also be capital. So whenever we are going to add it on, but the total production is not increasing with that input, then the cost of that input has to be higher on certain price. That will increase in the total cost or the marginal cost. So when there will be increase in the cost and there will not be increase in the total production, at the end there will be not the profit or the incremental part of the revenue but it will add in the loss. So this aspect that we have to keep in mind that the law of diminishing marginal productivity is basically explaining our point. So in the marginal product, when we use only one product, we see that it begins to decline. So that is the point of decision where the entrepreneur has to decide that either he has to change a combination or after this point, if he will continue to produce, he will be producing but at a certain cost and he will be producing but not at the incremental rate but rather in decrease or the decline for. Now if we look at the process generally, in the short run, the aspects of capital in machinery, we can say the building, we can say the land, it mostly change. So in the short run, the variable change, we can say it may be the labour. But if I look at some other examples, compared to labour, we can say it can be certain amount of fertilizer for the agriculture and at the same time for industry, we can say it can be energy, it can be coal and like any other input. So any input that is variable, that is going to change and we are going to add on, we are going to increase. So start may, when we more factor with certain combination of other fixed resources, add on, there are production possibility aspects. In that combination, if we accept any one production function and now we are adding a new unit of input, we will see that there is increase in the total output. But that total increase is a particular point where we will go and see that relative to that constraint, it has stagnated and it is not increasing. And next, if we go and see, there will be a possibility that it is decreasing. So here it will be the starting of the diminishing returns and the diminishing marginal productivity. And this will be that point where during the production process, the entrepreneur has to decide that this is not his profitable range and he has to start or stop his production. Stable may, when we see that in the start, this is the aspect where marginal productivity is increasing and again there is a part. Now from 7, it is going to decline and decline and it reach to 0. So it is the diminishing marginal productivity. And if it add this aspect, we are not going to stop our production further. It will increase in the diminishing absolute productivity, meaning that is that range where we will see that the total production it will decline. So this marginal physical productivity, it is our yardstick that with the help of the love of diminishing marginal physical productivity an entrepreneur can utilize this to decide at which state he has to increase the input, how much to increase and at which stage he has to stop adding that input further in the production setup to avoid the certain loss in the future. If we look at this graphically, we have already drawn that this is one average product and this is our marginal product. So the marginal physical product is maximum at a point and after that it declines to zero. And after this, if we go down further, this aspect is when the total production it will decline. And when we are increasing, this is that phase when total production is increasing at increasing rate and second phase, this it shows that total production still increasing but at decreasing rate and this is the third part where total production it will be decreasing. So this love diminishing marginal physical productivity it helps the entrepreneur to decide about the production stages.