Supply of a commodity is functionally related to its price. The law of supply rated to this function relationship between price of a commodity and its supply. In contrast to the inverse relationship between the quantity demanded and the changes in price the quantity supplied generally varies directly with price. That is the higher the price the large is the quantity supplied of a commodity.

The supply schedule and supply curve reflect the law of supply. According to the law of supply when the price of a commodity rises, the quantity supplied of it in the market increases and when the price of a commodity falls its quantity demanded decrease other factors deeming supply remaining the same. Thus according to the law of supply, the quantity supplied of a commodity is directly or positively related to price. It is due to this direct relationship between price of a commodity and its quantity supplied that the supply curve of a commodity slopes upward to right as seen from supply curve SS in when price of wheat rises from $ 520 to $ 530 per quintal the quantity supplied of wheat in the market increase from 200 quintals to 225 quintals per period.