The situation in which more of a commodity is purchased at its existing price is called Increase in Demand.
Given below table and figure illustrate it:
Price (in Rs.) |
Quantity Demanded of X (Units) |
10 |
20 |
10 |
30 |

When price of the commodity is Rs. 10 per unit, 20 units are demanded. Even when price remains constant, consumers continue demanding 30 units. It may be due to more alternative uses of a commodity or other such variables. It shows that when the price remains constant, the demand of commodity increases.