Physics is a branch of natural science that seeks to understand the fundamental laws of the universe. It explores how matter, energy, force, and motion interact across space and time — from the tiniest subatomic particles to the vastness of the cosmos.
🟦Mechanics
Mechanics deals with the motion of objects and the forces acting upon them.
🔑 Major Concepts:
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Kinematics: Study of motion (displacement, velocity, acceleration) without considering causes.
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Dynamics: Concerned with forces and their effects (Newton’s Laws of Motion).
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Work, Energy & Power: Study of energy transformation and capacity to do work.
📌 Examples:
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Projectile Motion: Path of a ball thrown in the air – follows a parabolic curve.
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Free Fall: Acceleration due to gravity (≈ 9.8 m/s²).
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Conservation of Energy: Energy remains constant in a closed system (e.g., roller coaster).
🟦Thermodynamics
Thermodynamics studies heat, temperature, and their relation to energy and work.
🔑 Key Laws:
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First Law: Energy is conserved (cannot be created or destroyed).
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Second Law: Entropy (disorder) in an isolated system always increases.
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Third Law: As temperature approaches absolute zero, entropy approaches a minimum.
📌 Examples:
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Heat Engine: Converts fuel energy into mechanical work (e.g., car engine).
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Refrigerator: Uses work to remove heat from a cold area and release it outside.
🟦 Electromagnetism
Electromagnetism explores electricity and magnetism and their interrelationship.
🔑 Key Concepts:
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Coulomb’s Law: Force between electric charges.
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Faraday’s Law of Induction: A Changing magnetic field induces current (EMF).
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Maxwell’s Equations: Unified equations describing electric and magnetic fields.
📌 Examples:
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Electric Current: Flow of electrons in wires (e.g., home appliances).
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Electromagnets: A Magnetic field produced by an electric current.
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Transformers: Step up/down voltage using electromagnetic induction.
🟦Optics
Optics focuses on light and its interactions with matter.
🔑 Key Concepts:
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Reflection & Refraction: Bouncing and bending of light.
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Lenses & Mirrors: Image formation by concave/convex mirrors or lenses.
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Interference & Diffraction: Wave interactions causing fringe patterns.
📌 Examples:
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Concave Mirrors: Used in telescopes and shaving mirrors.
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Optical Fibers: Use total internal reflection to transmit data.
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Rainbows: Light dispersion through water droplets forms a color spectrum.
🟦Modern Physics
Modern Physics includes 20th-century advancements like relativity and quantum theory.
🔑 Key Concepts:
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Theory of Relativity: Describes gravity, time dilation, and space curvature (Einstein).
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Quantum Mechanics: Explains atomic and subatomic behavior.
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Photoelectric Effect: Light ejects electrons from metal surfaces.
📌 Examples:
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GPS: Accounts for relativistic effects to give accurate positioning.
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Particle Accelerators: Collide particles at high speed to study matter.
🟦Waves and Oscillations
This area studies repetitive motion and wave propagation.
🔑 Key Concepts:
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Simple Harmonic Motion (SHM): Restoring force is proportional to displacement (e.g., spring).
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Waves: Transfer of energy without matter movement.
📌 Examples:
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Sound Waves: Longitudinal waves in air or water (e.g., tuning fork).
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Light Waves: Electromagnetic waves that can travel through a vacuum (e.g., sunlight).
🟦Fluid Mechanics
Fluid Mechanics deals with the behavior of liquids and gases.
🔑 Key Concepts:
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Bernoulli’s Principle: Faster-moving fluid has lower pressure.
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Archimedes’ Principle: Buoyant force equals the displaced fluid’s weight.
📌 Examples:
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Aircraft Design: Uses Bernoulli’s principle for lift.
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Hydraulic Systems: Use pressure to lift heavy loads (e.g., car lifts).
🟦Atomic and Nuclear Physics
This field investigates atoms, their nuclei, and nuclear reactions.
🔑 Key Concepts:
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Radioactivity: Emission of radiation from unstable nuclei.
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Fission and Fusion: Splitting or combining nuclei to release energy.
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Bohr’s Model: Electrons orbit at specific energy levels.
📌 Examples:
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Nuclear Power Plants: Generate electricity via fission.
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Carbon Dating: Estimates age using radioactive decay.
🟦Conservation Laws
These laws state that certain physical quantities remain constant in closed systems.
🔑 Key Concepts:
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Conservation of Mass & Energy: Total remains constant.
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Conservation of Momentum: Total momentum is conserved unless an external force acts.
📌 Examples:
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Elastic Collision: Kinetic energy and momentum are conserved.
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Rocket Propulsion: The Momentum of the gas expelled pushes the rocket forward.
🟨 🔑 Quick Recap – Important Topics for Competitive Exams
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🌀 Mechanics: Newton’s Laws, Work–Energy, Motion
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🔥 Thermodynamics: Laws, Heat Engines
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⚡ Electromagnetism: Coulomb’s Law, Maxwell’s Equations
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🔍 Optics: Reflection, Refraction, Lenses
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🌌 Modern Physics: Relativity, Quantum Mechanics
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🎵 Waves & Oscillations: Sound & Light Waves
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💧 Fluid Mechanics: Bernoulli’s & Archimedes’ Principles
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☢️ Atomic/Nuclear Physics: Radioactivity, Fission & Fusion
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⚖️ Conservation Laws: Energy & Momentum
📝 Sample Questions for Practice
Q1. What is the principle behind the working of a hydraulic press?
A. ✅ Pascal's Law – Pressure applied to a confined fluid is transmitted equally in all directions.
Q2. Which of the following is not an electromagnetic wave?
A. Radio Waves
B. Microwaves
C. ✅ Sound Waves
D. X-rays
Q3. What is the Law of Conservation of Energy?
A. ✅ Energy cannot be created or destroyed, only transformed from one form to another.
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