Explain the law of variable proportions with the help of total product curve. Use diagram.

Explanation

According to the Law of Variable Proportions as only one input is increased, other remaining unchanged, the total product increases at an increasing rate, then at a decreasing rate and ultimately falls.

Phase I In the first phase, TP increases at an increasing rate upto point A.
Phase II In the second phase. TP increases at a diminishing rate between point A & B
Phase III In the third phase, TP starts falling beyond point B.