Standard of Comparison (Large and Small Physical Quantities)

 Standard of Comparison Explained | CBSE Class 11 Physics | NEET Notes 

Standard of Comparison in Physics with real-life examples for NEET and CBSE students.

- Dr. Sanjaykumar Pawar 

Q. 1.4 Explain this statement clearly:

“To call a dimensional quantity ‘large’ or ‘small’ is meaningless without specifying a standard for comparison.”

Answer (CBSE Topper Style)

A dimensional physical quantity has both magnitude and unit. Whether it is called large or small depends on what it is being compared with.

Therefore, simply saying that a quantity is "large" or "small" has no meaning unless a standard or reference quantity is mentioned.

Example:

• A distance of 10 m is large compared to the size of a classroom but very small compared to the distance between two cities.

Hence, every statement describing a dimensional quantity as large or small should include a suitable standard of comparison.

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Reframing the given statements

(a) Atoms are very small objects.

Reframed Statement:
Atoms are very small compared to ordinary objects, such as a grain of sand or a pinhead.

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(b) A jet plane moves with great speed.

Reframed Statement:
A jet plane moves with great speed compared to road vehicles, but its speed is much smaller than the speed of light.

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(c) The mass of Jupiter is very large.

Reframed Statement:
The mass of Jupiter is very large compared to the mass of the Earth (or any other planet like Mars).

---

(d) The air inside this room contains a large number of molecules.

Reframed Statement:
The air inside this room contains a very large number of molecules compared to the number of people or other visible objects present in the room.

---

(e) A proton is much more massive than an electron.

Answer:
This statement is already meaningful because it clearly specifies the standard of comparison (electron).

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(f) The speed of sound is much smaller than the speed of light.

Answer:
This statement is already meaningful because it compares the speed of sound with the speed of light, providing a clear standard of comparison.

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Final Answer (Exam Points)

• A quantity can be called large or small only with respect to a specified standard or reference.
• Without comparison, such statements are meaningless.

Corrected Statements:

(a) Atoms are very small compared to ordinary objects.
(b) A jet plane moves with great speed compared to road vehicles.
(c) The mass of Jupiter is very large compared to the mass of the Earth.
(d) The air inside this room contains a very large number of molecules compared to the number of people in the room.
(e) No change required, as the comparison is with an electron.
(f) No change required, as the comparison is with the speed of light. 

NEET Master Learning Structure (NMLS)

हर टॉपिक के लिए एक यूनिवर्सल फॉर्मेट

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1. Topic Name

Chapter: Units and Measurements

Topic: Standard of Comparison (Large & Small Quantities)

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2. One-Line Definition (Exam Definition)

Rule:

किसी भी भौतिक राशि (Physical Quantity) को "बड़ा" या "छोटा" तभी कहा जा सकता है जब उसके साथ तुलना (Comparison) का मानक (Standard) दिया गया हो।

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3. Why? (Concept Building)

याद रखने वाला नियम

👉 बड़ा या छोटा = हमेशा तुलना

यदि तुलना नहीं है तो कथन अधूरा है।

---

4. Visual Flow Chart

Physical Quantity
        │
        ▼
Large / Small ?
        │
        ▼
Compared With?
      /      \
    Yes      No
    │         │
Meaningful  Meaningless

---

5. Memory Trick (Mnemonic)

Mnemonic

"LSC"

L → Large

S → Small

C → Comparison

Large or Small ⇒ Comparison Must

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दूसरा आसान Mnemonic

"No Comparison = No Conclusion"

(NC = NC)

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6. Quick Table

Statement	Comparison Given?	Correct / Incorrect
Atom is small	❌ No	Incorrect
Atom is smaller than a grain of sand	✅ Yes	Correct
Jet is fast	❌ No	Incorrect
Jet is faster than a car	✅ Yes	Correct
Proton is heavier than electron	✅ Yes	Correct
Speed of sound is less than speed of light	✅ Yes	Correct

---

7. Comparison Table

Quantity	Compared With	Final Statement
Atom	Everyday objects	Very small
Jet Plane	Car	Very fast
Jupiter	Earth	Very massive
Air Molecules	Humans	Very large number
Proton	Electron	Much heavier
Sound	Light	Much slower

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8. Mind Map

             Large / Small
                    │
        ┌───────────┼───────────┐
        │           │           │
     Heavy       Fast       Long
        │           │           │
        └───────────┼───────────┘
                    │
          Need Comparison
                    │
           Otherwise Wrong

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9. Common Mistakes

❌ Atom is very small.

✔ Atom is very small compared to everyday objects.

---

❌ Car is very fast.

✔ Car is faster than a bicycle.

---

❌ Jupiter is very massive.

✔ Jupiter is much more massive than Earth.

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10. Examiner's Favourite Questions

Type-1

Explain why comparison is necessary.

---

Type-2

Rewrite the statement correctly.

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Type-3

Which statement is meaningful?

---

Type-4

Assertion-Reason

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Type-5

Choose the incorrect statement.

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11. NEET Trick

Whenever you read these words

Large

Small

Heavy

Light

Fast

Slow

High

Low

Long

Short

Immediately ask

"Compared to What?"

यदि उत्तर मिल गया

✅ Statement Correct

यदि उत्तर नहीं मिला

❌ Statement Incorrect

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12. PYQ Thinking Method

Question पढ़ते ही

STEP-1

Physical Quantity पहचानो

↓

STEP-2

Large/Small लिखा है?

↓

STEP-3

Comparison दिया है?

↓

Yes → Correct Statement

No → Wrong Statement

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13. 10-Second Revision

✔ Large = Relative

✔ Small = Relative

✔ Heavy = Relative

✔ Fast = Relative

✔ Comparison Must

✔ No Comparison = No Meaning

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14. Golden Rule (100% Exam Point)

यदि किसी वाक्य में Large, Small, Heavy, Light, Fast, Slow, High या Low लिखा हो, तो तुरंत जाँचें कि तुलना (Comparison) दी गई है या नहीं।

यदि तुलना नहीं दी गई है, तो कथन वैज्ञानिक रूप से अधूरा (Meaningless) माना जाएगा।

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15. One-Line Formula

Large/Small + Comparison = Meaningful Statement

Large/Small − Comparison = Meaningless Statement

NEET Practice Question Bank

Chapter: Units and Measurements

Topic: Standard of Comparison (Large & Small Quantities)

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Section A: Direct MCQs (Single Correct Option)

Easy Level

Q1.

Which of the following statements is scientifically meaningful?

A. A mountain is very high.

B. An atom is very small.

C. A proton is more massive than an electron.

D. A river is very long.

✅ Answer: C

Explanation: Only option C provides a standard of comparison.

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Q2.

Which statement is incomplete?

A. Earth is larger than the Moon.

B. Light travels faster than sound.

C. Jupiter is more massive than Earth.

D. A train is very fast.

✅ Answer: D

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Moderate Level

Q3.

Which statement correctly follows the principle of comparison?

A. Molecules are tiny.

B. A jet plane is fast compared to a bicycle.

C. A room contains many molecules.

D. The Sun is hot.

✅ Answer: B

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Q4.

Which statement is NOT meaningful?

A. A proton is heavier than an electron.

B. Sound travels slower than light.

C. Mercury is smaller than Earth.

D. Iron is very heavy.

✅ Answer: D

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Hard Level

Q5.

Which option correctly identifies all meaningful statements?

1. Atom is very small.

2. Proton is heavier than electron.

3. Speed of light is greater than speed of sound.

4. Jupiter is very massive.

Options

A. 1 and 4

B. 2 and 3

C. 1,2,3

D. All

✅ Answer: B

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Section B: Statement-Based Questions

Q6.

Statement I

Every physical quantity described as "large" or "small" requires a comparison.

Statement II

Without a standard of comparison, such statements are scientifically incomplete.

A. Both statements are true and II explains I.

B. Both true but II does not explain I.

C. I true II false.

D. I false II true.

✅ Answer: A

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Q7.

Statement I

The statement "An atom is very small" is scientifically complete.

Statement II

A meaningful statement must include a standard of comparison.

A. TT

B. TF

C. FT

D. FF

✅ Answer: C

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Section C: Assertion & Reason

Q8.

Assertion (A)

"The speed of sound is much smaller than the speed of light."

Reason (R)

The statement specifies a standard for comparison.

A. Both A and R are true, and R is the correct explanation.

B. Both true but R is not the explanation.

C. A true R false.

D. A false R true.

✅ Answer: A

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Q9.

Assertion

"A jet plane moves with great speed."

Reason

The statement gives the comparison standard.

A. TT Correct Explanation

B. TT Wrong Explanation

C. TF

D. FT

✅ Answer: C

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Section D: Match the Columns

Column I

A. Atom

B. Proton

C. Sound

D. Jupiter

Column II

1. Compared with Earth

2. Compared with Electron

3. Compared with Light

4. Compared with Everyday Objects

Correct Matching

A → 4

B → 2

C → 3

D → 1

Answer

A-4

B-2

C-3

D-1

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Section E: Diagram-Based Question

Flow Chart

          Statement
               │
               ▼
      Large / Small ?
               │
        ┌──────┴──────┐
        │             │
Comparison Given?   No Comparison
        │             │
        ▼             ▼
Meaningful      Meaningless

Question

The statement

"Gold is heavy."

lies in which branch?

A. Meaningful

B. Meaningless

C. Dimensionless

D. Scalar

✅ Answer: B

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Section F: Higher Order Thinking (HOTS)

Q10.

A student writes

"The Earth is very large."

The teacher marks it incorrect.

Which correction is most appropriate?

A. Earth is large compared to the Moon.

B. Earth is always large.

C. Earth is absolutely large.

D. Earth has a large radius.

✅ Answer: A

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Q11.

Which one of the following is an example of a relative statement?

A. Length is measured in metre.

B. Speed of light is constant.

C. The Himalayas are higher than the Aravalli Hills.

D. Mass is a fundamental quantity.

✅ Answer: C

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Section G: NEET PYQ-Type Mixed MCQs

Q12.

Identify the meaningful statements.

1. Air contains many molecules.

2. Jupiter is more massive than Earth.

3. Electron is lighter than proton.

4. Mountain is very high.

Options

A. 1,2

B. 2,3

C. 1,3

D. All

✅ Answer: B

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Q13.

Which of the following words usually require a comparison to become scientifically meaningful?

1. Large

2. Small

3. Fast

4. Heavy

Options

A. Only 1

B. 1 and 2

C. 1,2,3

D. All

✅ Answer: D

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Section H: Very Hard NEET Conceptual Question

Q14.

Which statement best explains why "The Sun is very large" is scientifically incomplete?

A. The Sun is not large.

B. Size has no unit.

C. No comparison standard has been specified.

D. The Sun's mass is unknown.

✅ Answer: C

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Section I: NEET Trap Question

Q15.

Which one is correctly written?

A. Atom is tiny.

B. Jupiter is huge.

C. Proton is much heavier than electron.

D. Car is fast.

✅ Answer: C

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Final Revision Trick

Whenever you read these words in a NEET question:

✔ Large

✔ Small

✔ Heavy

✔ Light

✔ Fast

✔ Slow

✔ High

✔ Low

Immediately ask:

👉 "Compared to What?"

If comparison is given → Correct

If comparison is missing → Incorrect or Incomplete

 Internal Links

From this article link to

✔ Physical Quantities

✔ Fundamental and Derived Quantities

✔ SI Units

✔ International System of Units

✔ Dimensions

✔ Dimensional Formula

✔ Dimensional Analysis

✔ Significant Figures

✔ Errors in Measurement

✔ Scientific Notation

✔ Order of Magnitude

✔ Accuracy and Precision

✔ Vernier Calipers

✔ Screw Gauge

✔ NCERT Class 11 Physics Chapter 2 Notes

✔ NEET Physics MCQ Collection

✔ Physics Formula Sheet

✔ Previous Year Questions 

“Meaning of large and small physical quantities depends on comparison”

  Meaning of Large & Small in Physics Explained | Class 11

- Dr.Sanjaykumar Pawar 

Physics becomes meaningful only when quantities are compared with a standard reference scale. 

🔗  Internal Links 

/class-11-physics-units-and-measurement

/dimensional-analysis-notes-class-11

/cbse-physics-important-questions-class-11

/physics-basic-concepts-scale-and-magnitude

/topper-answer-writing-skills-physics

🌟 CBSE Class 11 Physics

Topic: Meaning of “Large” and “Small” in Physical Quantities

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📘 Q1. Explain the statement clearly:

“To call a dimensional quantity ‘large’ or ‘small’ is meaningless without specifying a standard for comparison.”

✔ Answer:

In physics, a quantity cannot be described as large or small in absolute terms. Such descriptions are meaningful only when compared with a standard reference. Without comparison, these words have no scientific significance. For example, a mass may be large compared to a human body but small compared to Earth. Hence, a reference standard is necessary for meaningful interpretation.

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📘 Q2. Reframe the following statements appropriately:

(a) atoms are very small objects

Answer: Atoms are very small objects compared to ordinary visible objects, with size of the order of 10^-10 m.

(b) a jet plane moves with great speed

Answer: A jet plane moves with great speed compared to road vehicles, typically of the order of 10²–10³ km/h.

(c) the mass of Jupiter is very large

Answer: The mass of Jupiter is very large compared to Earth, approximately 1.9 × 10²⁷ kg.

(d) the air inside this room contains a large number of molecules

Answer: The air inside this room contains a very large number of molecules compared to macroscopic counting scales, about 10²⁵ molecules per cubic meter.

(e) a proton is much more massive than an electron

Answer: A proton is about 1836 times more massive than an electron.

(f) the speed of sound is much smaller than the speed of light

Answer: The speed of sound (~340 m/s) is much smaller than the speed of light (3 × 10⁸ m/s).

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📝 Short Notes

In physics, terms like “large” and “small” are relative, not absolute. A physical quantity is meaningful only when compared with a standard reference or another quantity.

Without specifying a comparison, such terms are scientifically incorrect because the same quantity may appear large in one context and small in another.

• Atoms are small compared to macroscopic objects (~10^-10 m).
• Jet planes are fast compared to vehicles but slow compared to satellites.
• Jupiter has a very large mass (~1.9 × 10²⁷ kg).
• Air contains ~10²⁵ molecules per m³.
• Proton is 1836 times heavier than electron.
• Speed of sound is negligible compared to speed of light.

Conclusion: Scientific statements must always include a reference or numerical comparison to be meaningful.

🌟 CBSE Class 11 Physics Practice Set

Topic: Meaning of “Large” and “Small” in Physical Quantities

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📘 Practice Questions with Answers

Q1. Why is it meaningless to call a physical quantity “large” or “small” without comparison?

Answer: It is meaningless because physical quantities are relative. A value can be large in one context and small in another. Therefore, a standard of comparison is necessary.

Q2. Reframe: “Mount Everest is very high.”

Answer: Mount Everest is very high compared to most mountains, with a height of about 8848 m above sea level.

Q3. Reframe: “A bullet travels very fast.”

Answer: A bullet travels very fast compared to a car, typically with a speed of about 300–1000 m/s.

Q4. Reframe: “A bacteria is very small.”

Answer: A bacteria is very small compared to human cells, with size of the order of 10^-6 m.

Q5. Reframe: “The Earth is very massive.”

Answer: The Earth is very massive compared to human-scale objects, with mass approximately 6 × 10²⁴ kg.

Q6. Reframe: “Light travels extremely fast.”

Answer: Light travels extremely fast compared to all ordinary speeds, with speed 3 × 10⁸ m/s.

Q7. Reframe: “An electron has very small mass.”

Answer: An electron has very small mass compared to a proton, with mass 9.11 × 10^-31 kg.

Q8. Reframe: “The universe is very large.”

Answer: The universe is very large compared to the observable human scale, with size of the order of 10²⁶ m.

Q9. Reframe: “A drop of water contains many molecules.”

Answer: A drop of water contains a very large number of molecules compared to macroscopic counting, about 10²¹ molecules.

Q10. What is the correct scientific way to describe “large” or “small” quantities?

Answer: They should be described either by comparison with a standard reference or by using numerical values and order of magnitude.

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📝 Key Learning Point

In physics, all descriptions like “large”, “small”, “fast”, or “heavy” are meaningful only when a reference is given. Otherwise, they are subjective and scientifically incorrect.

🌟 CBSE Class 11 Physics Practice Set

Topic: Meaning of “Large” and “Small” in Physical Quantities

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📘 Practice Questions with Answers

Q1. Why is it meaningless to call a physical quantity “large” or “small” without comparison?

Answer: It is meaningless because physical quantities are relative. A value can be large in one context and small in another. Therefore, a standard of comparison is necessary.

Q2. Reframe: “Mount Everest is very high.”

Answer: Mount Everest is very high compared to most mountains, with a height of about 8848 m above sea level.

Q3. Reframe: “A bullet travels very fast.”

Answer: A bullet travels very fast compared to a car, typically with a speed of about 300–1000 m/s.

Q4. Reframe: “A bacteria is very small.”

Answer: A bacteria is very small compared to human cells, with size of the order of 10^-6 m.

Q5. Reframe: “The Earth is very massive.”

Answer: The Earth is very massive compared to human-scale objects, with mass approximately 6 × 10²⁴ kg.

Q6. Reframe: “Light travels extremely fast.”

Answer: Light travels extremely fast compared to all ordinary speeds, with speed 3 × 10⁸ m/s.

Q7. Reframe: “An electron has very small mass.”

Answer: An electron has very small mass compared to a proton, with mass 9.11 × 10^-31 kg.

Q8. Reframe: “The universe is very large.”

Answer: The universe is very large compared to the observable human scale, with size of the order of 10²⁶ m.

Q9. Reframe: “A drop of water contains many molecules.”

Answer: A drop of water contains a very large number of molecules compared to macroscopic counting, about 10²¹ molecules.

Q10. What is the correct scientific way to describe “large” or “small” quantities?

Answer: They should be described either by comparison with a standard reference or by using numerical values and order of magnitude.

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📝 Key Learning Point

In physics, all descriptions like “large”, “small”, “fast”, or “heavy” are meaningful only when a reference is given. Otherwise, they are subjective and scientifically incorrect.

Physical Quantities & SI Units: Notes for CBSE Class 11 & NEET |

Understanding the fundamental building blocks of Physics: The 7 Base SI Units.

🔗 Internal Link 

 * To a Physics Chapter: "Now that you've mastered units, check out our guide on [Dimensional Analysis and Errors]."

 * To a Practical Guide: "Learn how these units apply in the laboratory with our [Class 11 Physics Practical Manual]."

 * To a Foundation Course: "New to high school physics? Start with [The Basics of Mathematical Tools in Physics]."

Units and Measurement

The Subatomic Scale: At the level of 10^-13 m, we enter the world of the atomic nucleus. This is the domain of Nucleons (Protons and Neutrons) and heavier elementary particles. These particles are bound together by the exchange of Gluons, the messengers of the strong nuclear force.

Physical Quantities

All quantities that can be measured are called physical quantities. In physics, we study these quantities and their inter-relationships (e.g., length, mass, force, work done).

Types of Physical Quantities

• Fundamental Quantity: Physical quantities which cannot be expressed in terms of any other physical quantities.
  Examples: Length, Mass, Time, Temperature.
• Derived Quantity: Physical quantities which are derived from fundamental quantities.
  Examples: Area, Density, Force.

Measurement

Measurement is the comparison of a physical quantity with a standard of the same physical quantity. A standard unit is essential for:

1. Accuracy
2. Convenience
3. Uniformity
4. Equal justice to all

Characteristics of a Standard Unit

A chosen unit should be: Consistent (Invariable), Available, Imperishable (Permanent), Convenient, and Reproducible.

Classification of Units

• Fundamental Unit: Used to measure fundamental quantities (e.g., Metre, Kilogram).
• Derived Unit: Used to measure derived quantities (e.g., Square metre for area, g/cm³ for density).

Systems of Units

System	Length	Mass	Time
FPS (British)	Foot (ft)	Pound (lb)	Second (s)
CGS (Gaussian)	Centimetre (cm)	Gram (g)	Second (s)
MKS	Metre (m)	Kilogram (kg)	Second (s)

International System of Units (SI)

The SI system is a modern modification of the MKS system. It is the most widely used system globally and consists of three categories:

• 7 Fundamental Quantities
• 2 Supplementary Quantities (Radian and Steradian)
• Derived Quantities

Physics: The Science of Measurement

Understanding the Subatomic Scale

When we talk about 10^-13 m to 10^-15 m, we are looking at the building blocks of matter:

• Nucleons: Protons and Neutrons (size approx. 0.8 x 10^-15 m).
• Gluons: The "glue" (massless particles) that hold quarks together within nucleons.
• Measurement Context: These are measured using Fermi (1 fm = 10^-15 m).

1. Physical Quantities

Anything that can be measured numerically and follows the laws of physics is a Physical Quantity.

Quantity	Type	Real-World Example / Relationship
Mass	Fundamental	Quantity of matter in an object (Scalar).
Length	Fundamental	Distance between two points.
Force	Derived	Mass × Acceleration (kg·m/s²).
Density	Derived	Mass / Volume (kg/m³).

Why do we need Standard Units?

Imagine buying cloth where the "meter" changed every day. Standards ensure:

• Invariability: The unit doesn't change with time or temperature.
• Reproducibility: A scientist in India and a scientist in Brazil get the same result.

2. Global Systems of Units

While the world has converged on SI Units, historical systems provide context for how we measure today:

System	Length	Mass	Time
FPS (British)	Foot (ft)	Pound (lb)	Second (s)
CGS (Gaussian)	Centimeter (cm)	Gram (g)	Second (s)
MKS (Standard)	Meter (m)	Kilogram (kg)	Second (s)

3. The SI System (Modern Standard)

The International System (SI) is the complete version of MKS. It includes:

• 7 Base Units: (Meter, Kilogram, Second, Ampere, Kelvin, Mole, Candela).
• 2 Supplementary Units: Radian (plane angle) and Steradian (solid angle).

Fundamental Quantities & SI Units

1. Comparison of Unit Systems

Physical Quantity	CGS (Gaussian)	MKS (Standard)	FPS (British)
Length	Centimetre (cm)	Metre (m)	Foot (ft)
Mass	Gram (g)	Kilogram (kg)	Pound (lb)
Time	Second (s)	Second (s)	Second (s)

2. The 7 Fundamental SI Units

The International System of Units (SI) is the modern form of the metric system. Below are the precise scientific definitions for the base units:

Length m

Unit: Metre

The distance traveled by light in vacuum in 1/299,792,458 of a second.

Mass kg

Unit: Kilogram

Defined by the mass of a platinum-iridium cylinder kept at the International Bureau of Weights and Measures.

Time s

Unit: Second

The duration of 9,192,631,770 periods of radiation from the transition between two hyperfine levels of Cesium-133.

Thermodynamic Temp. K

Unit: Kelvin

The fraction 1/273.16 of the thermodynamic temperature of the triple point of water.

Electric Current A

Unit: Ampere

The constant current which produces a force of 2 × 10⁻⁷ N/m between two parallel conductors of infinite length.

Luminous Intensity cd

Unit: Candela

The intensity of a blackbody of surface area 1m² at the temperature of freezing platinum under standard pressure.

Amount of Substance mol

Unit: Mole

The amount of substance containing as many elementary entities as there are atoms in 0.012 kg of carbon-12.

3. Supplementary Quantities

1. Plane Angle (Radian - rad): Defined as θ = arc / radius.

2. Solid Angle (Steradian - sr): Defined as Ω = Area / (Radius)².

Practice Module: Units & Measurement

Target: CBSE Class 11 & NEET 2026

Section A: Very Short Answer (1 Mark)

Q1. Define a Light Year.

View Solution

It is the distance traveled by light in vacuum in one year. 1 ly = 9.46 × 10¹⁵ m.

Section B: Multiple Choice Questions NEET Pattern

Q2. Which of the following is NOT a fundamental SI unit?

• (A) Ampere
• (B) Candela
• (C) Newton
• (D) Kelvin

View Solution

Correct Option: (C). Newton is a derived unit (kg·m/s²), while Ampere, Candela, and Kelvin are fundamental units.

Section C: Assertion & Reason

Directions: (A) Both A and R are true and R is the correct explanation. (B) Both A and R are true, but R is not the correct explanation. (C) A is true, R is false. (D) A is false, R is true.

Assertion (A): Light year and year, both measure time.
Reason (R): Because both have "year" in their name.

View Solution

Correct Option: (D). Assertion is false because Light Year is a unit of Distance, not time. Reason is true as a statement of naming, but does not justify the physics.

Section D: Descriptive Questions (3 & 5 Marks)

Q3. Distinguish between Fundamental and Derived units with two examples each.

View Solution

Fundamental Units: Independent units like Metre (m) and Kilogram (kg).
Derived Units: Units expressed in terms of base units, like Velocity (m/s) or Force (N).

Q4. State the characteristics of a standard unit of measurement. (Long Answer)

View Solution

A standard unit should be:

1. Invariable: It should not change with time or physical conditions.
2. Available: It should be easily accessible.
3. Reproducible: It can be recreated anywhere in the world.
4. Indestructible: It should be permanent.

Physical Quantities & Measurement

Comprehensive Question Bank for Class 11 Physics

CBSE PATTERN NEET PREP

I. Very Short Answer Questions (1 Mark)

1. What is meant by a "Physical Quantity"?

View Solution

All quantities that can be measured, either directly or indirectly, and in terms of which the laws of physics can be described are called physical quantities. Examples: Length, Mass, Force.

2. Distinguish between Fundamental and Derived quantities.

View Solution

Fundamental: Quantities that cannot be expressed in terms of others (e.g., Time, Temperature).
Derived: Quantities derived from fundamental ones (e.g., Area = Length × Breadth).

II. Multiple Choice Questions (NEET Pattern)

3. Which of the following is the fundamental unit in the FPS system for Mass?

• A) Gram
• B) Kilogram
• C) Pound
• D) Slug

View Solution

Correct Answer: C (Pound). In the FPS (British Engineering) system, the base units are Foot (length), Pound (mass), and Second (time).

4. The International System of Units (SI) is a modification of which system?

• A) FPS
• B) CGS
• C) MKS
• D) Gaussian

View Solution

Correct Answer: C (MKS). SI is an improved and extended version of the MKS system, including seven base and two supplementary units.

III. Assertion & Reason

Instructions:
(A) Both A and R are true and R is the correct explanation of A.
(B) Both A and R are true but R is NOT the correct explanation of A.
(C) A is true but R is false.
(D) A is false but R is true.

Assertion (A): Measurement is essentially a process of comparison.
Reason (R): A standard unit should be easily reproducible and invariable.

View Solution

Correct Answer: B. Both statements are factually correct. However, the reason (characteristics of a unit) does not explain the definition of measurement (the process of comparison).

IV. Long Answer Questions (5 Marks)

5. What are the essential characteristics of a standard unit? Why is SI preferred globally?

View Solution

Characteristics:

1. Invariability: It must not change with time or physical conditions (temperature, pressure).
2. Availability: It should be easily available for comparison.
3. Reproducibility: It should be possible to replicate the standard anywhere.
4. Permanency: It should not be perishable.

Why SI is Preferred: It is a coherent and rational system of units used worldwide, ensuring uniformity in scientific data exchange and international trade.

Quick Review: Unit Systems

System	Length	Mass	Time
CGS	cm	g	s
MKS	m	kg	s
FPS	ft	lb	s