Physics - Definition, Fundamentals, Types, Importance, Chapters, Topics

Did you know that even while sitting on a chair and reading this article, Physics is at work? Concepts like normal force, weight, and equilibrium come into play. Physics is a branch of science that explains how the entire world works. It helps us understand everything around us, from how objects move from here to there and how electricity powers our homes.

For instance, the recent landing of SpaceX’s Starship rocket was made possible by applying advanced principles of Physics. Physics isn’t just about theories—it’s a practical subject deeply connected to our daily lives and the technology we use.

Why is Physics Important?

Physics is a crucial subject for lower-level students starting in class 6 since it serves as the foundation for classes 11 and 12. For students who want to pursue careers in engineering medicine or a similar field, it is a crucial subject.

Many topics, including motion, the laws of motion, current electricity, magnetism, and more, are covered in the physics curriculum for classes 11 and 12. These topics are crucial not just for the board exam but also for competitive exams such as JEE, NEET and others.

Branches of Physics

There are a total of twenty-eight chapters of class 11 and class 12 physics which are divided into eight branches which we discuss below one by one.

Mechanics

Chapter 1: Units And Measurements

Units And Measurements is the very first chapter of the class 11 circular in which we study fundamental quantities, units, and measurement techniques, along with error analysis and significant figures. In the recent year of JEE Main total of thirty questions were asked from both sessions with a weight of 5%.

Some of the important topics of this chapter are:

• Significant Figures
• Applications Of Dimensional Analysis
• Dimensions Of Physical Quantities
• Dimensionless Quantities

Chapter 2: Motion In A Straight Line

Motion In A Straight Line is part of kinematics and the second chapter of class 11 class, in this chapter of mechanics we generally study the motion of objects along a straight path, focusing on velocity, acceleration, and equations of motion.

The below list is given for some of the very important topics which come under Motion In A Straight Line.

• Equation Of Motions
• Vector Addition And Vector Subtraction
• Kinematics Graphs

Chapter 3: Motion In A Plane

Motion In A Plane is also a part of kinematics and the third chapter of class 11 physics. In this chapter, we mainly study two-dimensional motion with concepts of vectors, Projectile Motion, Horizontal Projectile Motion, Equation Of Path Of A Projectile, Uniform circular motion and Relative velocity

Some advanced concepts of motion in a plane Chapter:

• Boat River Problem
• Rain-man Problem

Chapter 4: Laws of Motion

Laws Of Motion is the fourth chapter of class 11 which comes under the mechanics part. In this chapter of class 11, we study all three Newton's Laws Of Motion: Newton’s First Law Of Motion, Newtons Second Law of Motion and Momentum ,Newtons Third Law of Motion and their applications in analyzing Forces and dynamics.

Some of the advanced concepts of laws of motion chapter in which questions can be asked in competitive exams like JEE/NEET and other state-level exams.

• Motion of an Insect in the Rough Bowl
• Minimum Mass Hung from the String to Just Start the Motion
• Maximum Length Of Hung Chain
• Sticking Of Person With The Wall Of Rotor

Chapter 5: Work, Energy And Power

Kinetic and potential energy, the work-energy theorem, and the idea of power are all explained in Work, Energy And Power. Discussions of conservation laws are accompanied by real-world examples. In the past year, a total of 21 questions with a weight of 3.50 percent were asked during the January and April sessions.

Don't miss the important topic of this chapter which is listed below:

• Conservative And Non-conservative Forces
• Collision
• Conservative And Non-conservative Forces
• Vertical Circular Motion

Chapter 6: System Of Particles And Rotational Motion

The sixth chapter of Class 11, System Of Particles And Rotational Motion, focuses on the center of mass, motion of extended bodies, and rotational dynamics. Fundamental concepts like torque, angular momentum, and moment of inertia are discussed in detail. This chapter holds significant importance for entrance exams; in 2024, a total of 31 questions were presented from this chapter in JEE Main, highlighting its weightage in the syllabus.

Chapter 7: Gravitation

Gravitation is the last chapter of the mechanics part, In which we study Introduces the universal law of gravitation, Kepler’s laws, and orbital mechanics. It explains variations in gravity and its effects on motion. 19 questions were asked in JEE Main last year from this chapter.

Some of the important concept of this chapter are:

• Escape Velocity
• Gravitational Potential Energy
• Relation Between Gravitational Field And Potential
• Geostationary and polar satellites

Properties of Matter

In the second part of physics, we study two chapters: Mechanical Properties Of Solids and Fluid which are part of class 11 physics.

Chapter 8: Mechanical Properties Of Solid

The first chapter of the Properties of Matter section, Mechanical Properties Of Solids, focuses on elasticity, stress-strain relationships, and the mechanical properties of materials. It highlights Hooke’s law and the applications of elastic behaviour in real-life scenarios. This chapter holds significant importance in competitive exams, with more than 15 questions asked across both sessions of JEE Main 2024.

Chapter 9: Mechanical Properties Of Fluid

The second chapter on properties of matter Mechanical Properties Of Fluids explains fluid statics and dynamics, including buoyancy, viscosity, and Bernoulli's principle. Real-world phenomena like capillarity and fluid flow are discussed.

Key your eyes on some of the important concepts of properties of matter

• Relation Between Volumetric Strain, Lateral Strain And Poisson’s Ratio
• Stokes' law & Terminal Velocity
• Variation Of Pressure In An Accelerated Fluid
• Hooke’s Law
• Stress And Strain
• Stokes' Law And Terminal Velocity

Thermal Physics

After Mechanics and Properties of Matter, the third part of physics is Thermal Physics, which includes three chapters from Class 11:

Chapter 10: Thermal Properties Of Matter

In the tenth chapter of physics which is Thermal Properties Of Matter, we study heat transfer methods, thermal expansion, and specific heat capacities. It emphasizes real-life examples of thermal properties.

Chapter 11: Thermodynamics

Thermodynamics discusses the laws of thermodynamics, including energy conservation, entropy, and heat engines. Practical applications like refrigerators are included. More than 15 questions were asked in the recent year of JEE Main.

Chapter 12: Kinetic Theory

Kinetic Theory provides a microscopic view of gases, focusing on molecular motion, pressure, temperature, and their relationships in ideal gases.

We have seen what this chapter covers in short now see below some of the very important concepts of this section.

• Stefan Boltzmann Law
• Steady Conduction Heat Transfer
• Wien's Displacement Law
• Ideal Gas Equation
• Real Gas And Equation

Oscillations and Waves

Oscillations and Waves are divided into two chapters, chapter 13: Oscillations and Chapter 14: waves.

Chapter 13: Oscillations

This chapter focused on simple harmonic motion (SHM), damping, and forced oscillations. Applications in pendulums and oscillatory systems are studied, providing a base for understanding periodic motion.

Chapter 14: Waves

Waves chapter explains wave types, their properties, and the principle of superposition. It also discusses standing waves, resonance, and real-world applications of wave phenomena.

The last chapter of class 11 oscillation and wave is not only important for board exams but also for competitive exams like JEE Main/NEET and others. Some of the important concept of this chapter is given below:

• Terms associated with SHM
• Doppler Effect
• End Correction
• Newton's Formula For The Velocity Of Sound In Gas
• Time Period Of Torsional Pendulum
• Relation Between Phase Difference And Path Difference

Electricity and Magnetism

In this branch of physics, the focus shifts to Electricity and Magnetism, starting from Class 12 Physics. A total of seven chapters are included in this section, covering fundamental and applied concepts. Below, we will explore each chapter one by one, beginning with Electrostatics.

Chapter 1: Electric Charges And Fields

The first chapter of class 12 Electric Charges And Fields Introduces the nature of electric charge, Coulomb’s law, and electric field lines. Concepts of flux and Gauss's law are also discussed.

Chapter 2: Electrostatic Potential And Capacitance

Electrostatic Potential And Capacitance chapter starts with an explanation of electric potential, energy in charged systems, and the behaviour of capacitors in circuits.

From both of these chapters also known as electrostatic combined chapters, almost 40 questions were asked in JEE Main 2024 from both of the sessions with a weightage of 6.50%.

• Relation Between Electric Field And Potential
• Electric Field Due To An Infinitely Long Charged Wire
• Electric Flux Through Cone Or Disc
• Potential Due To Hollow Conductiong, Solid Conducting, Hollow Non Conducting
• Torque On An Electric Dipole In A Uniform Electric Field

Chapter 3: Current Electricity

The third chapter of the class 12 circular Current Electricity is one of the very important chapters not only for the board exam but also for the engineering and medical entrance test. This was one of the high-weighted chapters in JEE Main 2024 with almost 50 questions being asked in recent years.

• Resistors In Series And Parallel Combinations
• Calculation Of Resistance By Symmetry
• Resistance And Resistivity
• Resistor Colour Code
• Change Of Resistance In Wires By Stretching

Chapter 4: Magnetism And Matter

Magnetism And Matter Focus on magnetic fields, Earth’s magnetism, and magnetic properties of materials like diamagnetism and ferromagnetism.

Chapter 5: Moving Charges And Magnetism

This chapter Moving Charges And Magnetism focuses on the magnetic effects produced by moving charges and current-carrying conductors. Key topics include Biot-Savart law, Ampere's circuital law, and the force on a moving charge in a magnetic field (Lorentz force). The chapter also discusses the working of devices like cyclotrons and moving coil galvanometers, which utilize these principles.

• Lorentz Force
• Ampere's Circuital Law And Its Applications

Chapter 6: Electromagnetic Induction

This is the sixth chapter of class 12 physics in which we study about Faraday’s and Lenz’s laws, induced emf, and applications in generators and transformers.

• Lenz's Law
• Faraday's law of induction

Chapter 7: Alternating Current

Alternating Current is the last chapter of the Electricity and Magnetism section, which studies the behaviour of AC in RLC circuits, resonance, and power transfer. Practical uses like transformers are discussed. From electromagnetic Induction and alternating currents which are chapters 6 and 7 a total of 45 questions were asked in JEE Main 2024 after current electricity this is the second high weitage chapter.

• LC Oscillations
• Series LCR Circuit
• Series RC Circuit
• Average And Rms Value Of Alternating Current And Voltage

Electromagnetic Waves

Chapter 8:Electromagnetic Waves

In this branch of Waves, one chapter is included Electromagnetic Waves which is part of class 12, in which we studied Maxwell's equations, the electromagnetic spectrum, and applications like communication and radar technology.

• Displacement Current
• Maxwell's 4 Equations
• Energy Density And Intensity Of EM Waves

Optics

In this branch of physics, we studied two chapters which are Chapter 8 and Chapter 9. In the recent year of JEE Main, a total of 38 questions were present from this section with a weightage of 6.33% which is 3rd highest among the overall chapters.

Chapter 9: Ray Optics And Optical Instruments

This Ray Optics And Optical Instruments chapter explains image formation through lenses and mirrors, and the working principles of optical instruments like microscopes and telescopes. More focus on sign conversion which is a crucial part of solving the example of this chapter.

Chapter 10: Wave Optics

The ninth chapter of class 12 physics Wave Optics focuses on light as a wave, covering phenomena like interference, diffraction, and polarization. Applications in optical devices are explored.

• Resolving power of optical instruments
• Lens Maker's formula
• YDSE with thin slab
• Relation Between Object And Image Velocity In Lens

Modern Physics

This is the last branch of physics in which four chapters are added, which are all chapters from class 12 physics.

Chapter 11: Dual Nature Of Matter And Radiation

The first chapter of modern physics Dual Nature Of Matter And Radiation Explains the particle-wave duality, photoelectric effect, and de Broglie wavelength. It bridges classical and quantum physics.

• The Photoelectric Effect
• Electron Emission

Chapter 12: Atoms

The second chapter of Modern Physics Atoms discusses atomic models, spectral lines, and energy transitions in hydrogen-like atoms.

Chapter 13: Nuclei

Nuclei chapter explains nuclear structure, binding energy, and phenomena like radioactivity and nuclear fission and fusion.

Almost 40 questions were asked in JEE main last year from atoms and nuclei, see some of the important concepts of this chapter which are given below.

• Line Spectra Of Hydrogen Atom
• Energy Level - Bohr's Atomic Model
• Bohr Model Of The Hydrogen Atom
• Nuclear Fission
• Radioactive Decay

Chapter 14: Semiconductor Electronics

Semiconductor Electronics: Materials, Devices And Simple Circuits is the last chapter of class 12 physics which covers the basics of semiconductors, diodes, transistors, and their applications in electronic circuits and logic gates.

• Logic Gates
• P-N Junction As A Rectifier
• Zener diode as a voltage regulator

NCERT Resources and Supplements for CBSE Students

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Physics In Different Exams

The Physics subject is presented in various exams in the form of subjective, objective, and numerical answer-based questions, as detailed in the table below.

How to Solve Physics Numerical

Solving physics numerical is one of the challenging tasks for many students but with the right approach, you can master this skill. Follow these steps to solve numerical effectively:

Step 1: Reading Questions

The first step in solving a numerical is reading the question and writing down the given data. Don't read the entire question in one go; instead, read it line by line, write down the given data, and try to represent the problem in the form of a diagram.

Step 2: Use the proper Unit

While writing the given data, ensure that all values are converted to the same unit. For example, if speed is given in km/h and m/s, convert both to either km/h or m/s.

Step 3: Identify Formuale

In the third step, you have the given data and know what you need to find. This means you know your starting point (given data) and your destination (what you need to calculate). The next task is to identify the correct formula, which acts as the path to reach the solution.

Step 4: Substitute Values and Solve

Once you’ve identified the formula, substitute the known values along with their units. Be cautious while substituting to avoid missing terms or misplacing decimals. Solve step by step, keeping the calculations neat and organized.

Step 5: Check the Final Units

After solving, check if the answer has the correct unit. For example:

• A speed calculation should result in units like m/s or km/h.
• Energy should have units like joules (J).

If the units don’t match the expected quantity, revisit your calculations for errors.

Step 6: Verify the Answer

Think critically about the answer:

• Does it make sense in the given context?
• Is the magnitude reasonable?
• Have you rounded off the values appropriately?

If something seems off, recheck the steps to identify where you might have gone wrong.