Q.If the supply curve is a straight line parallel to the vertical axis (Y-axis), supply of the good is called as _________. (Fill up the blank)

Price Elasticity of Supply: From the Market to the Formula

Imagine you run a small bakery. One morning, a sudden wedding order comes in — customers are willing to pay double your usual price for 100 extra loaves of bread. Can you instantly produce those 100 loaves? Probably not. You have limited ovens, a fixed amount of dough prepared, and only two hands. You might manage 20 extra loaves by working faster, but 100 is impossible today.

Now imagine the same order comes, but you have a month's notice. You can hire extra help, buy more flour, and even rent another oven. Suddenly, producing 100 extra loaves is easy.

This difference — how much quantity supplied changes when price changes — is exactly what Price Elasticity of Supply (PES) measures.

The Precise Meaning

Price Elasticity of Supply tells us the percentage change in quantity supplied divided by the percentage change in price. It answers: "If the price rises by 1%, by what percentage will sellers increase the quantity they offer?"

Where:

• $E_s$ = Price Elasticity of Supply
• $\% \Delta Q_s$ = Percentage change in quantity supplied
• $\% \Delta P$ = Percentage change in price

Since supply curves are upward-sloping (higher price → higher quantity supplied), $E_s$ is always positive. A value of 2 means a 1% price rise leads to a 2% increase in quantity supplied. A value of 0.5 means only a 0.5% increase.

Why It Matters: The Time Factor

The bakery example reveals the single most important determinant of PES: time.

• Very short period (market period): Supply is fixed. You cannot increase output at all. Think of fresh flowers at a market — whatever was picked today is all there is. PES = 0 (perfectly inelastic). The supply curve is vertical.
• Short period: You can increase output by using existing capacity more intensively — overtime, faster machines, but no new factories. PES is low but positive (between 0 and 1). The supply curve slopes upward gently.
• Long period: You can build new factories, train workers, adopt new technology. Supply becomes highly responsive. PES > 1 (elastic). The supply curve is flatter.

Other Factors That Affect PES

1. Nature of the good: Agricultural goods (wheat, rice) have low PES in the short run because crops take a season to grow. Manufactured goods (pens, shirts) have higher PES because production can be ramped up quickly.
2. Storage possibility: Goods that can be stored (canned food, gold) have higher PES because sellers can release stockpiles when prices rise. Perishable goods (milk, fish) have lower PES.
3. Complexity of production: A simple product like a paper clip has high PES; a complex product like an aircraft has low PES even in the long run.
4. Availability of inputs: If raw materials and labour are easily available, supply is more elastic.

Interpreting the Numbers