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Law of Demand: Schedule, Curve, Exceptions (ICSE 10)

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EconomicsICSE Class 10 · Demand and Supply

Demand and the Law of Demand: Schedule, Curve and Exceptions (ICSE Class 10)

Updated 17 October 2026 · Fact-checked

Demand is the quantity of a commodity a consumer is willing and able to buy at a given price in a given period. The law of demand states that, other things remaining the same, the quantity demanded rises when price falls and falls when price rises, so the demand curve slopes downward. Market demand is the sum of all individual demands at each price. Giffen goods, prestige goods and fear of a future price rise are exceptions.

As price falls from ₹50 to ₹10, quantity demanded rises, and the market curve lies right of A and B because it adds their demands.

Illustration drawn for QuestionBuddy.

Understand Demand, Types of Demand and Law of Demand

Meaning. Demand needs three things: desire, ability to pay and willingness to spend. It is always stated at a price and for a period (per day, per month).

Types of demand.

  • Individual and market demand.
  • Joint (complementary) demand: goods needed together, such as a car and petrol.
  • Composite demand: one good with several uses, such as electricity or milk.
  • Derived demand: arises from the demand for another product, such as bricks from houses.
  • Competitive demand: substitutes, such as tea and coffee.
  • Direct demand: goods that satisfy wants directly, such as food.

Law of demand. Other things remaining constant, quantity demanded varies inversely with price. The "other things" are income, tastes, prices of related goods, expectations and population.

Demand schedule and curve.

Price per kg (₹)A's demand (kg)B's demand (kg)Market demand (kg)
50213
40437
306511
208715
1010919

Plot price on the Y-axis and quantity on the X-axis; the curve slopes downward. The market curve is the horizontal sum of the individual curves, so it lies to the right of each.

Why the curve slopes down (brief reasons). At a lower price existing buyers buy more, and new buyers enter. Cheaper goods also become more attractive than substitutes.

Exceptions to the law of demand.
1. Giffen goods: a staple of the very poor; when its price rises they have less to spend on other food and buy more of it.
2. Articles of distinction (prestige goods): diamonds, luxury cars; more demanded at a higher price as they show status.
3. Expectation of a future price rise: buy more now.
4. Ignorance, where a higher price is taken as a sign of quality.
5. Emergencies such as war or famine.

Demand, Types of Demand and Law of Demand: key facts

Demand (meaning)
  • Desire
  • Ability to pay
  • Willingness to spend
  • At a price in a period
Law of demand
  • Price up, quantity demanded down
  • Inverse relation
  • Ceteris paribus
Market demand
Sum of all individual quantities at each price
Exceptions
  • Giffen goods
  • Prestige goods
  • Expected price rise
  • Ignorance
  • Emergencies

How to answer Demand, Types of Demand and Law of Demand questions

Schedule questions: add quantities row by row; curve questions: price on Y, quantity on X, downward-sloping line.

  1. 1Write the law in words and add "other things remaining constant".
  2. 2For market demand, add the individual quantities at each price.
  3. 3Plot price (Y) against quantity (X), join the points, label DD.
  4. 4State the relation (inverse) and the slope (downward).
  5. 5For exceptions give the name and a one-line reason.

Demand, Types of Demand and Law of Demand in real life

The idea, met in an everyday situation. Answer the question in your own words, then compare with the model answer. The one-line hook is what to remember.

Samosas at the school canteen

Suppose a school canteen sells a samosa at ₹20, and Aman buys 2 each day. When the price falls to ₹10, he buys 4. At ₹10 his friend Zoya, who did not buy at ₹20, now buys 1.

What do these facts show about individual and market demand?

Try it first, then show the solutionSolution
  1. Aman: price falls from ₹20 to ₹10 and quantity rises from 2 to 4.
  2. Market demand at ₹20 = 2 + 0 = 2; at ₹10 = 4 + 1 = 5.
  3. Zoya is a new buyer attracted by the lower price.

Answer: Quantity demanded rises as price falls (law of demand); market demand rises from 2 to 5 as old buyers buy more and new ones join.

Memory hook: Lower price, more buyers, more bought.

Tricks to remember Demand, Types of Demand and Law of Demand

Short memory aids. Say each one aloud once, then use it on a question the same day.

  • Inverse = see-saw

    When price goes up, quantity goes down.

    Use it when: Law of demand.

  • GPE

    Giffen, Prestige, Expectation: exceptions.

    Use it when: Remembering exceptions.

  • Add across

    Market demand: add the people, not the prices.

    Use it when: Schedules.

Demand, Types of Demand and Law of Demand: solved examples

Ordered from board level to HOTS. Try each one before you open the solution.

Example 1: Direction of relation · 1 mark · MCQBoard level

According to the law of demand, when the price of a good falls, the quantity demanded:
(a) rises
(b) falls
(c) stays the same
(d) becomes zero

Try it first, then show the solutionSolution
  1. Inverse relation between price and quantity.

Answer: (a)

Example 2: Market demand · 2 marks · Short answerBoard level

At ₹30 per kg, A demands 6 kg, B demands 5 kg and C demands 4 kg. Find market demand at ₹30. At ₹20 each of them demands 2 kg more. Find market demand at ₹20. (2 marks)

Try it first, then show the solutionSolution
  1. At ₹30: 6 + 5 + 4 = 15 kg.
  2. At ₹20: A 8, B 7, C 6; total 21 kg (check: 15 + 3 × 2 = 21).

Answer: 15 kg at ₹30; 21 kg at ₹20.

Example 3: Schedule to curve · 3 marks · Short answerHarder board level

Using the schedule in the concept section (market demand 3, 7, 11, 15, 19 kg at ₹50, 40, 30, 20, 10), describe how you will draw the market demand curve and find market demand at ₹25 from the schedule. (3 marks)

Try it first, then show the solutionSolution
  1. Mark price on the Y-axis and quantity on the X-axis, plot the five points, join them and label DD.
  2. The points lie on a straight line: each ₹10 fall in price adds 4 kg.
  3. At ₹25 (halfway between ₹30 and ₹20), quantity = (11 + 15) ÷ 2 = 13 kg, assuming the line is straight. This is an estimate, not a schedule value.

Answer: Downward-sloping line; about 13 kg at ₹25 by reading the straight line.

Example 4: Exceptions · 4 marks · Long answerHarder board level

Explain any three exceptions to the law of demand. (4 marks)

Try it first, then show the solutionSolution
  1. Giffen goods: a poor family buys more of a cheap staple when its price rises.
  2. Prestige goods: a diamond is bought more at a higher price for status.
  3. Expected price rise: people buy more now before the price goes up further.
  4. In each case the demand curve slopes upward, not downward.

Answer: Giffen goods, prestige goods and expectation of a price rise.

Example 5: Individual and market curve · 3 marks · Short answerHOTS / competency

Two consumers have demand of 2 and 1 units at ₹50 and 4 and 3 units at ₹40 (as in the schedule). A third consumer joins the market and demands 2 units at ₹50 and 2 units at ₹40. Find the new market demand at both prices and say how the market curve changes. (3 marks)

Try it first, then show the solutionSolution
  1. At ₹50: 2 + 1 + 2 = 5 units. At ₹40: 4 + 3 + 2 = 9 units.
  2. Earlier market demand was 3 and 7, so both quantities rise by 2.
  3. The market demand curve shifts to the right because the number of buyers has increased.

Answer: 5 and 9 units; the market curve shifts rightwards.

Where students lose marks in Demand, Types of Demand and Law of Demand

The slips examiners see most often, and what to write instead.

  • Mistake: Forgetting "other things remaining constant"

    Law incomplete.

    Wrong working

    Quantity falls when price rises.

    Right working

    Other things remaining constant, quantity falls when price rises.

    Do this: Always add the assumption.

    Usually costs: 1 mark.

  • Mistake: Axes reversed

    Habit from maths.

    Wrong working

    Price on X-axis.

    Right working

    Price on Y-axis, quantity on X-axis.

    Do this: Label both axes.

    Usually costs: 1 mark.

  • Mistake: Adding prices for market demand

    Mixing rows.

    Wrong working

    Market demand = sum of prices.

    Right working

    Add quantities at each price.

    Do this: Add across the same row.

    Usually costs: 1 mark.

Exam tips

  • Draw a neat labelled diagram when a curve is asked.
  • Show schedule additions row by row.
  • Give exceptions with a one-line reason.

Practice questions on Demand, Types of Demand and Law of Demand

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

  1. Q1 · 1 mark · MCQBoard level

    Which of the following is an example of joint demand?
    (a) Tea and coffee
    (b) Pen and ink
    (c) Rice and wheat
    (d) Bus and train

    Hint

    Used together.

    Answer

    (b)

  2. Q2 · 3 marks · Short answerBoard level

    State the law of demand and write its assumptions. (3 marks)

    Hint

    Other things constant.

    Answer

    Other things remaining constant, quantity demanded rises when price falls and falls when price rises. Assumed constant: income, tastes, prices of related goods, expectations, population.

  3. Q3 · 3 marks · Short answerHarder board level

    Prepare a market demand schedule from these individual demands: price ₹10, 20, 30; A: 9, 6, 3 units; B: 7, 5, 1 units. (3 marks)

    Hint

    Add the rows.

    Answer

    ₹10: 16 units; ₹20: 11 units; ₹30: 4 units.

  4. Q4 · 3 marks · Short answerHarder board level

    What are Giffen goods? Explain why the law of demand fails for them. (3 marks)

    Hint

    Staple of the poor.

    Answer

    Giffen goods are cheap staple foods of the poor. When their price rises, the poor can no longer afford better foods and buy more of the staple. So quantity demanded rises with price.

  5. Q5 · 3 marks · Short answerHOTS / competency

    At ₹40 the market demand for a good is 100 units and at ₹32 it is 130 units. By how much per cent did price fall and by what per cent did quantity demanded rise? What does this show about the law of demand? (3 marks)

    Hint

    Percentage change = change ÷ original × 100.

    Answer

    Price fall = (40 − 32) ÷ 40 × 100 = 20%. Quantity rise = (130 − 100) ÷ 100 × 100 = 30%. Quantity rises when price falls, in line with the law (this is the idea behind elasticity).

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

  1. 1.Relation between price and demand?Show answer

    Inverse.

  2. 2.Slope of demand curve?Show answer

    Downward.

  3. 3.Market demand is?Show answer

    Sum of individual demands at each price.

  4. 4.Name an exception.Show answer

    Giffen goods.

  5. 5.Joint demand example?Show answer

    Car and petrol.

Demand, Types of Demand and Law of Demand: frequently asked questions

What is the law of demand?

Other things constant, quantity demanded rises as price falls and vice versa.

Why does the demand curve slope downward?

Because the quantity demanded rises when price falls: old buyers buy more and new buyers enter.

What are exceptions to the law of demand?

Giffen goods, prestige goods, expected price rise, ignorance and emergencies.