B. The Law of Supply
Like the law of demand, the law of supply demonstrates the quantities that will be sold at a
certain price. But unlike the law of demand, the supply relationship shows an upward slope.
This means that the higher the price, the higher the quantity supplied. Producers supply more
at a higher price because selling a higher quantity at a higher price increases revenue.
A, B and C are points on the supply curve. Each
point on the curve reflects a direct correlation
between quantity supplied (Q) and price (P). At
point B, the quantity supplied will be Q2 and the
price will be P2, and so on. (To learn how
economic factors are used in currency trading,
read Forex Walkthrough: Economics.)
Time and Supply
Unlike the demand relationship, however, the
supply relationship is a factor of time. Time is
important to supply because suppliers must, but cannot always, react quickly to a change in
demand or price. So it is important to try and determine whether a price change that is caused
by demand will be temporary or permanent.
Let's say there's a sudden increase in the demand and price for umbrellas in an unexpected
rainy season; suppliers may simply accommodate demand by using their production equipment
more intensively. If, however, there is a climate change, and the population will need umbrellas
year-round, the change in demand and price will be expected to be long term; suppliers will
have to change their equipment and production facilities in order to meet the long-term levels
of demand.
C. Supply and Demand Relationship
Now that we know the laws of supply and demand, let's turn to an example to show how supply
and demand affect price.
Imagine that a special edition CD of your favorite band is released for $20. Because the record
company's previous analysis showed that consumers will not demand CDs at a price higher
than $20, only ten CDs were released because the opportunity cost is too high for suppliers to
produce more. If, however, the ten CDs are demanded by 20 people, the price will subsequently
rise because, according to the demand relationship, as demand increases, so does the price.
Consequently, the rise in price should prompt more CDs to be supplied as the supply
relationship shows that the higher the price, the higher the quantity supplied.
If, however, there are 30 CDs produced and demand is still at 20, the price will not be pushed
up because the supply more than accommodates demand. In fact after the 20 consumers have