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What is the Law of Diminishing Marginal Utility (economic principle)?
Grade Level:
Class 8
Law, Civic Literacy, Economics, FinTech, Geopolitics, Personal Finance, Indian Governance
Definition
What is it?
The Law of Diminishing Marginal Utility states that as a person consumes more and more units of a specific good or service, the additional satisfaction (utility) they get from each extra unit tends to decrease. Simply put, the more you have of something, the less extra joy each new unit brings.
Simple Example
Quick Example
Imagine you're very hungry after school and your mom offers you a hot samosa. The first samosa tastes amazing! The second one is also good, but maybe not as mind-blowing as the first. By the time you eat the fifth samosa, you might feel full, and the sixth one might not give you any extra happiness at all, or even make you feel sick.
Worked Example
Step-by-Step
Let's say you love playing video games. We can measure your 'satisfaction points' for each hour you play:
Step 1: You play for the 1st hour. You are super excited! You get 100 satisfaction points.
---Step 2: You play for the 2nd hour. Still fun, but a little less exciting than the very first hour. You get 80 satisfaction points.
---Step 3: You play for the 3rd hour. You're starting to feel a bit tired or bored. You get 50 satisfaction points.
---Step 4: You play for the 4th hour. You really don't feel like playing anymore. You get only 10 satisfaction points.
Answer: The 'marginal utility' (extra satisfaction) decreased from 100 to 80 to 50 to 10 with each additional hour of playing, showing diminishing marginal utility.
Why It Matters
This principle helps us understand why people make certain choices about what to buy and how much. It's crucial for businesses to decide how to price their products and for governments to plan public services. Understanding this helps in careers like marketing, finance, and even personal budgeting.
Common Mistakes
MISTAKE: Thinking that total satisfaction decreases | CORRECTION: Total satisfaction usually increases, but at a slower rate. It's the *additional* satisfaction from each new unit that decreases.
MISTAKE: Confusing 'utility' with 'money' | CORRECTION: Utility is satisfaction or happiness, which can be hard to measure, not just the monetary value of a good.
MISTAKE: Believing this law applies only to physical goods | CORRECTION: This law applies to services too, like watching movies, listening to music, or getting advice.
Practice Questions
Try It Yourself
QUESTION: If you drink a glass of water when you are very thirsty, you get a lot of satisfaction. Will the 10th glass of water give you the same amount of satisfaction? | ANSWER: No, the 10th glass of water will likely give you much less, or even negative, satisfaction because of diminishing marginal utility.
QUESTION: A mobile game gives you 50 points for the first level, 40 for the second, and 30 for the third. Is this an example of diminishing marginal utility? Explain. | ANSWER: Yes, it is. The additional points (satisfaction) you get from each new level are decreasing (50, then 40, then 30), which shows diminishing marginal utility.
QUESTION: Your friend loves mangoes. He eats one and gets 100 'joy units'. The second gives him 80 units, and the third gives 50 units. If the fourth mango makes him feel sick (-20 units), what is his total joy after 4 mangoes? What is the marginal utility of the 4th mango? | ANSWER: Total joy after 4 mangoes = 100 + 80 + 50 - 20 = 210 joy units. The marginal utility of the 4th mango is -20 joy units.
MCQ
Quick Quiz
What happens to the additional satisfaction you get from consuming more units of a product, according to the Law of Diminishing Marginal Utility?
It stays the same.
It increases.
It decreases.
It first increases then decreases rapidly.
The Correct Answer Is:
C
The Law of Diminishing Marginal Utility states that the additional satisfaction (marginal utility) from each extra unit consumed decreases, even if total satisfaction might still be rising.
Real World Connection
In the Real World
This law explains why companies like Netflix or Spotify offer different subscription plans. After watching many movies, the 'utility' of watching one more might decrease, so they need to offer new content or features to keep you subscribed. Similarly, when you buy a new smartphone, the first one brings huge joy, but buying a second identical one immediately after would bring very little extra satisfaction.
Key Vocabulary
Key Terms
Utility: The satisfaction or happiness a person gets from consuming a good or service | Marginal: Refers to the 'additional' or 'extra' unit | Consumption: The act of using goods and services | Diminishing: Becoming less and less
What's Next
What to Learn Next
Now that you understand diminishing marginal utility, you can explore concepts like consumer equilibrium and demand curves. These ideas build on how individual satisfaction influences overall market behavior and pricing.
