Demand/supply; elasticity; welfare - Economics IB Study Notes
Overview
Have you ever wondered why the price of your favorite video game changes, or why sometimes everyone wants a new toy but there aren't enough to go around? That's what **demand and supply** are all about! They are like two invisible forces that decide how much stuff is made and how much it costs. Then we'll look at **elasticity**, which is like asking: 'How much does the price (or something else) have to change before people stop buying or making stuff?' It helps us understand if people are super sensitive to price changes or if they don't really care. Finally, **welfare** isn't about feeling good, but about how much happiness and benefit buyers and sellers get from all this buying and selling. It helps us see if the market is doing a good job making everyone happy, kind of like checking if a party is fun for all the guests!
What Is This? (The Simple Version)
Imagine you really want a new toy (let's say a super cool robot). How many robots are made, and how much they cost, depends on two big ideas:
-
Demand: This is how much of a good or service buyers want to buy at different prices. Think of it like your friends all wanting that new robot. If it's cheap, lots of people want it. If it's super expensive, maybe only a few rich kids will buy it.
- The Law of Demand: This is a fancy way of saying that usually, if the price of something goes down, people will want to buy more of it. If the price goes up, people will want to buy less of it. It makes sense, right?
-
Supply: This is how much of a good or service sellers are willing to sell at different prices. Think of it like the company that makes the robots. If they can sell robots for a high price, they'll want to make and sell lots of them to earn more money. If the price is low, they might not bother making many.
- The Law of Supply: This means that usually, if the price of something goes up, sellers will want to sell more of it. If the price goes down, they'll want to sell less of it.
These two forces, demand and supply, are always trying to find a balance, like a seesaw. Where they meet, that's the equilibrium (say: ee-kwil-LIB-ree-um) – the 'just right' price and quantity where buyers are happy with the price and sellers are happy with the amount they sell.
Real-World Example
Let's use the example of ice cream on a hot summer day.
-
Demand: It's a scorching hot day. Everyone wants ice cream! At $2 a scoop, maybe 100 people want ice cream. If it was $1 a scoop, maybe 200 people would want it. If it was $5 a scoop, maybe only 20 people would buy it. This shows how demand changes with price.
-
Supply: The ice cream shop owner looks at the weather. If they can sell ice cream for $5 a scoop, they'll hire extra staff, open earlier, and make tons of ice cream to sell. If they can only sell it for $1 a scoop, they might not even bother opening, or they'll only make a small batch.
-
Equilibrium: Imagine the shop owner tries selling at $4 a scoop. They make 80 scoops, but only 40 people want to buy it. Uh oh, too much ice cream! So, they lower the price. They try $2 a scoop. Now, they make 50 scoops, and 50 people want to buy it! Perfect! This is the equilibrium price ($2) and equilibrium quantity (50 scoops) where everyone is happy. There's no leftover ice cream and no one is left wanting it.
How Elasticity Works (How Sensitive Are We?)
Imagine you're trying to push a shopping cart. How much it moves when you push it depends on how heavy it is, right? **Elasticity** is similar; it measures how much one thing changes when another thing changes. 1. **Price Elasticity of Demand (PED)**: This tells us how much the **quantity demanded...
Unlock 3 More Sections
Sign up free to access the complete notes, key concepts, and exam tips for this topic.
No credit card required · Free forever
Key Concepts
- Demand: The amount of a good or service that buyers are willing and able to purchase at various prices.
- Supply: The amount of a good or service that sellers are willing and able to offer for sale at various prices.
- Equilibrium: The point where the quantity demanded equals the quantity supplied, setting the market price and quantity.
- Elasticity: A measure of how much one economic variable responds to a change in another economic variable.
- +5 more (sign up to view)
Exam Tips
- →Always draw clear, labeled diagrams for demand and supply shifts, showing the old and new equilibrium points.
- →When explaining elasticity, always state whether it's 'elastic' or 'inelastic' and explain *why* (e.g., 'because there are many substitutes').
- +3 more tips (sign up)
More Economics Notes