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NCERT Class 11 Physics Chapter 1 Notes Physical World - Download PDF

NCERT Class 11 Physics Chapter 1 Notes Physical World - Download PDF

Edited By Vishal kumar | Updated on Jan 30, 2024 02:59 PM IST

Revision Notes for Class 11 Physics Chapter 1 Physical World - Download Free PDF

Effective study material, particularly short notes, is critical in exam preparation because it allows for quick revision during class tests, exams, assignments, or question-solving sessions. Recognising this, Careers360 experts have carefully created NCERT Class 11th Physics Notes Chapter-wise. These notes are useful not only for board or state exams but also for competitive exams such as NEET and JEE Mains.

This page contains well-organized and expertly written Physical World class 11 notes. These revision CBSE notes, based on the latest NCERT Syllabus, provide a planned and systematic approach to revision. Class 11 physics chapter 1 notes are designed in such a way that students can quickly review key concepts. Furthermore, the Physical World notes class 11 are available in PDF format, allowing students to download and use them without the need for an internet connection. This accessibility ensures that students can review the material at any time and from any location, enhancing their exam preparation.

Also, students can refer,

NCERT Class 11 Physics Chapter 1 Notes -Quick Revision Notes


Science is a methodical and systematic pursuit that seeks to understand our surroundings through careful observations, experiments, and verifications.

The scientific method consists of a series of interconnected steps, which include:

  • Observations in a Systematic Approach: Scientists begin by collecting systematic and detailed data on natural phenomena. These observations lay the groundwork for further investigation.
  • Reasoning: Scientists engage in reasoning after making observations, drawing logical connections between observed facts. This step aids in the development of hypotheses or potential explanations for observed phenomena.
  • Simulation in Mathematics: Mathematical simulations are used in many scientific disciplines, particularly those involving quantifiable data. This could include employing mathematical models to represent and comprehend observed phenomena.
  • Theoretical Forecast: Scientists make theoretical predictions based on reasoning and mathematical simulations. These forecasts are frequently incorrect.
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Physics is an amazing science that teaches us about how things work in the real world. It's like reading the universe's rulebook. Mechanics (how things move), electromagnetism (how electricity and magnets work), thermodynamics (how heat and energy flow), and modern physics are all branches of physics.

From 1600 to 1900, people developed three major ideas in physics, which they called Classical Physics. They investigated how things move (classical mechanics), how heat works (thermodynamics), and how electricity and magnets interact (electromagnetism).

However, as smart scientists continued to learn, they realised that these traditional ideas couldn't explain everything. So, around 1905, they came up with some new and interesting ideas in what is now known as Modern Physics. This brought us things like Special Relativity (which talks about super-fast things) and Quantum Mechanics (which explores the tiniest building blocks of nature).

Physics' Scope and Excitement

Physics explores a wide range of phenomena, which can be neatly divided into two major domains: macroscopic and microscopic.

Macroscopic Domain: This domain includes phenomena observed at larger scales, such as galaxies and the universe, as well as those observed in laboratories, on Earth, and even on astronomical scales.

Microscopic Domain: The microscopic domain, on the other hand, focuses on the smallest scales, delving into atomic, molecular, and nuclear phenomena.

Also, Mesoscopic Physics, a newly recognised third domain, has emerged. This domain operates in the middle, dealing with hundreds of atom groups.

Physics has an incredibly wide and exciting scope. It encompasses objects ranging in size from the vastness of the Universe (measured in astronomical units (1025 metres) to the incredibly minute size of a nucleus (as small as 10-14 metres). This range of scales demonstrates physics' versatility in exploring and comprehending the world around us.

Relationships Between Physics and Other Sciences

Physics in Relation to Chemistry: Physics is critical in explaining chemistry phenomena such as chemical bonding, atomic numbers, and complex structures. These aspects are frequently understood by applying physics principles such as electrostatic forces. Furthermore, physics-guided techniques such as X-ray diffraction help to unravel the complexities of chemical structures.

Physics in Relation to Biological Sciences: Physics' inventions prove invaluable in the field of biology. Optical microscopes, which were developed using physics principles, aid in the study of biological samples. Electron microscopes allow for a more in-depth examination of biological cells. X-rays, for example, are used extensively in biological sciences, and radioisotopes, another physics product, are used in cancer research and treatment.

Physics in Relation to Astronomy: Physics is closely related to astronomy, which uses giant telescopes developed in the field to observe planets. The use of radio telescopes, a physics innovation, extends astronomers' observational capabilities to the far reaches of the universe.

Physics Related to Other Sciences: Physics provides a foundation for understanding a variety of phenomena in other sciences. Biophysics, oceanography, seismology, and other interdisciplinary fields benefit from using physical laws to investigate and explain various natural processes.

Fundamental Forces in Nature

There are many forces in the world, some of which we see in our daily lives and others which are far too small to notice. All of these forces, however, can be traced back to a set of super basic forces known as Fundamental Forces.

Gravitational Force:

  • It is caused by the mass of two bodies. The stronger the gravitational pull between the bodies, the greater their mass.
  • Gravity is always attractive. It attracts objects, causing them to collide, planets to orbit, and galaxies to form.
  • Gravity operates throughout the universe. It works in all objects, from the smallest particles to the most massive galaxies.
  • One of its most notable characteristics is its infinite range. Gravity never gives up; it stretches indefinitely across space.
  • Despite its pervasiveness, gravity is regarded as a weak force in comparison to other fundamental forces. It is approximately 1038 times weaker than the strong nuclear force that exists within atomic nuclei.

Electromagnetic Force:

  • It is caused by stationary or moving electrical charges.
  • It could be attractive or repulsive.
  • It operates on charged particles;
  • It has an infinite range, and It is 1036 times stronger than gravitational force but 10-2 times stronger than strong nuclear force.

Strong nuclear force:

  • Interact with Nucleons
  • It could be attractive or repulsive.
  • It has a very short range, within nuclear size (10-15 m).
  • It is nature's most powerful force.

Weak Nuclear force:

  • Operate within nucleons, which are elementary particles such as electrons and neutrinos.
  • It appears itself during radioactive b decay.
  • It has a very short range of 10-15 m.
  • 10-13 times more powerful than the Strong nuclear force.

Conserved Quantities:

Conserved quantities are the superheroes of stability in physics. These are the things that remain constant no matter what happens around them.

Let's take a look at a few of them:

  1. Total Mechanical Energy: you have a moving object. It can move faster or slower, but its total mechanical energy (the sum of its kinetic and potential energy) remains constant. It's akin to saying, "Hey, no matter how you're moving or where you are, the total energy you've got is always gonna be the same.
  2. Linear Momentum and Angular Momentum: If you have a lot of things moving or spinning, their total linear momentum (for straight-line motion) and total angular momentum (for spinning or rotating) will remain constant. It's as if they've made a promise to stay as spinny or quick as they were before.

Conservation Laws:

In physics, a conservation law is a fundamental principle that states that a specific quantity remains constant during physical processes. These laws are the result of extensive observations and experiments, and they have been validated using various scientific methods. Conservation laws are well-established and fundamental to our understanding of physical system behaviour.

Law of Conservation of Energy: An isolated system's total energy remains constant over time. Although energy can change forms and transform from one type to another, the total amount of energy in the system remains constant.

This law is universal in its application, encompassing all physical processes and phenomena. The total energy within a closed system obeys this law, from celestial bodies to microscopic particles.

The Law of Mass Conservation: The Law of Mass Conservation is a fundamental principle in physics and chemistry that states that the total mass of the system remains constant during any chemical or physical process. Mass can change shape or location, but the total mass before and after the process remains constant.

This law is frequently referred to as the conservation of matter, emphasising that matter is neither created nor destroyed. Instead, it goes through transformations like chemical reactions or physical changes while maintaining a constant total mass.

The Law of Mass Conservation applies in chemical reactions where substances combine or break apart. The total mass of the reactants equals the total mass of the products, demonstrating matter conservation.

Law of conservation of linear momentum: The Law of Conservation of Linear Momentum is a fundamental principle in physics that states that if no external forces act on an isolated system, its total linear momentum remains constant.

Linear momentum is the product of an object's mass and its velocity. It is a vector quantity, meaning it has both magnitude and direction.

Law of conservation of angular momentum: The Law of Conservation of Angular Momentum is a basic physics principle that states that If no external torques act on a system, its total angular momentum remains constant.

Laws of Physics related to technology

Physics Principle
Technology Application
Principle of Physics TechnologyBroad application in technology
Electromagnetic InductionElectricity Generation
Laws of ThermodynamicsSteam, Petrol, or Diesel Engine
Electromagnetic Waves PropagationRadio, TV, Phones
Nuclear Chain ReactionNuclear Reactor for Power
Newton's Second & Third LawRocket Propulsion
Bernoulli’s TheoremAirplanes
Population InversionLasers
X-raysMedical Diagnosis
Ultra High Magnetic FieldsSuperconductors
Digital ElectronicsComputers and Calculators

Significance of NCERT Class 11 Physics Chapter 1 Notes

  • Aligned with Curriculum: NCERT notes are designed to align with the prescribed curriculum, ensuring that students cover all of the important topics and concepts outlined in the CBSE Physics Syllabus in Class 11.
  • Clarity and Simplicity: These Physical World class 11 notes are written in clear and simple language to help students understand complex physics concepts.
  • Comprehensive Coverage: The Physical World Notes class 11 covers the entire chapter, summarising key points, formulas, and principles. This provides students with a unified view of the entire content.
  • Facilitates Revision: CBSE class 11 physics ch 1 notes are useful revision tools. Students can use these notes to quickly review key concepts prior to exams, ensuring a better understanding of the material.
  • PDF Resource: Students can easily access ch 1 physics class 11 notes because they are available for free. They can be used in both physical and digital formats, allowing for greater study flexibility.
  • Competitive Exams: This NCERT Class 11 Physics chapter 1 notes can also be used to prepare for competitive exams like VITEEE, BITSAT, JEE Main, NEET, and others by covering the core concepts of the CBSE Physics Syllabus in Class 11.

NCERT Class 12 Notes Chapter-Wise

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Subject Wise NCERT Solutions

Frequently Asked Question (FAQs)

1. Are all of the important derivations addressed in the chapter 1 notes for Class 11. Physics?

No, the NCERT notes for Class 11 Physics chapter 1 do not include all of the important derivations. This NCERT note summarizes the chapter's important points and equations and can be used to review the Physical World.

2. What do you mean by Gravitational Force?

Gravitational force is the universal attraction between masses, described by Newton's law of universal gravitation. 

3. How crucial is the chapter for the CBSE board exam, and how might these Class 11 Physical World notes help?

From the notes for Class 11 Physics chapter 1, students should expect 4 to 6 mark questions, and they can use this note for quick revision to assist them to improve their grades.

4. What is Weak Nuclear Force as per CBSE Class 11 Physics chapter 1 notes?

The weak nuclear force, discussed in CBSE Class 11 Physics Chapter 1 notes, is a fundamental force responsible for certain types of radioactive decay processes in atomic nuclei, mediated by W and Z bosons.

5. What do you understand with the term Physics?

Physics is a fundamental science that aims to comprehend natural processes that occur in our universe. 

6. Is CBSE class 11 physics ch 1 notes useful for JEE?

Yes, CBSE Class 11 Physics Chapter 1 notes provide a foundational understanding that is useful for JEE preparation, but supplementary study materials and focused practice are also recommended for comprehensive exam readiness.


Get answers from students and experts

A block of mass 0.50 kg is moving with a speed of 2.00 ms-1 on a smooth surface. It strikes another mass of 1.00 kg and then they move together as a single body. The energy loss during the collision is

Option 1)

0.34\; J

Option 2)

0.16\; J

Option 3)

1.00\; J

Option 4)

0.67\; J

A person trying to lose weight by burning fat lifts a mass of 10 kg upto a height of 1 m 1000 times.  Assume that the potential energy lost each time he lowers the mass is dissipated.  How much fat will he use up considering the work done only when the weight is lifted up ?  Fat supplies 3.8×107 J of energy per kg which is converted to mechanical energy with a 20% efficiency rate.  Take g = 9.8 ms−2 :

Option 1)

2.45×10−3 kg

Option 2)

 6.45×10−3 kg

Option 3)

 9.89×10−3 kg

Option 4)

12.89×10−3 kg


An athlete in the olympic games covers a distance of 100 m in 10 s. His kinetic energy can be estimated to be in the range

Option 1)

2,000 \; J - 5,000\; J

Option 2)

200 \, \, J - 500 \, \, J

Option 3)

2\times 10^{5}J-3\times 10^{5}J

Option 4)

20,000 \, \, J - 50,000 \, \, J

A particle is projected at 600   to the horizontal with a kinetic energy K. The kinetic energy at the highest point

Option 1)


Option 2)

\; K\;

Option 3)


Option 4)


In the reaction,

2Al_{(s)}+6HCL_{(aq)}\rightarrow 2Al^{3+}\, _{(aq)}+6Cl^{-}\, _{(aq)}+3H_{2(g)}

Option 1)

11.2\, L\, H_{2(g)}  at STP  is produced for every mole HCL_{(aq)}  consumed

Option 2)

6L\, HCl_{(aq)}  is consumed for ever 3L\, H_{2(g)}      produced

Option 3)

33.6 L\, H_{2(g)} is produced regardless of temperature and pressure for every mole Al that reacts

Option 4)

67.2\, L\, H_{2(g)} at STP is produced for every mole Al that reacts .

How many moles of magnesium phosphate, Mg_{3}(PO_{4})_{2} will contain 0.25 mole of oxygen atoms?

Option 1)


Option 2)

3.125 × 10-2

Option 3)

1.25 × 10-2

Option 4)

2.5 × 10-2

If we consider that 1/6, in place of 1/12, mass of carbon atom is taken to be the relative atomic mass unit, the mass of one mole of a substance will

Option 1)

decrease twice

Option 2)

increase two fold

Option 3)

remain unchanged

Option 4)

be a function of the molecular mass of the substance.

With increase of temperature, which of these changes?

Option 1)


Option 2)

Weight fraction of solute

Option 3)

Fraction of solute present in water

Option 4)

Mole fraction.

Number of atoms in 558.5 gram Fe (at. wt.of Fe = 55.85 g mol-1) is

Option 1)

twice that in 60 g carbon

Option 2)

6.023 × 1022

Option 3)

half that in 8 g He

Option 4)

558.5 × 6.023 × 1023

A pulley of radius 2 m is rotated about its axis by a force F = (20t - 5t2) newton (where t is measured in seconds) applied tangentially. If the moment of inertia of the pulley about its axis of rotation is 10 kg m2 , the number of rotations made by the pulley before its direction of motion if reversed, is

Option 1)

less than 3

Option 2)

more than 3 but less than 6

Option 3)

more than 6 but less than 9

Option 4)

more than 9

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