Can You Explain Classical Production Function?

The classical P.F. is concerned with the short run and this production function states that production depends upon unit of labor only while capital etc. is kept constant it is as:
Q = f (L) K.Classical are of the view that keeping the other factors constant if we go on employing the units of labor. The total production will increase at different rates. In other words the rate of change in total product which is called marginal product may increase may remain constant and may decrease.

Traditionally speaking by employing more labor if marginal product (MP) increase such will demonstrate the operation of, law of increasing returns. If MP remains constant such depicts the situation of law of constant returns and MP falls such situation means the law of decrease returns. All this denotes that the classical production function describes the three law of production. But now a day these three laws of return are presented with one law, the variables of variables proportion.
By having employed a certain number of labors whatsoever is produced by firms represents the total output of the firm. If firm produces 50 motorcycles by employing 10 labors such will represents total output or total product of the firm.