Introduction to Physics

• Physics is a natural science that studies matter, its fundamental constituents, motion and behavior through space and time, and related entities of energy and force.

Core Concepts

• Physics covers a wide range of phenomena, from subatomic particles to galaxies.
• Deals with fundamental laws of nature governing the behavior of matter and energy.
• It uses mathematical models and experimentation to analyze, explain, and predict physical phenomena.

Branches of Physics

• Classical Mechanics: Studies the motion of macroscopic objects under the action of forces.
  • Key concepts include Newton's laws of motion, energy, work, and momentum.
• Thermodynamics: Deals with heat, work, and energy transfer.
  • Involves the study of systems, their properties, and the laws governing the flow of heat.
• Electromagnetism: Explores the interaction of electric and magnetic fields.
  • Main concepts include electric charge, electric fields, magnetic fields, and electromagnetic waves.
• Optics: Studies the behavior and properties of light.
  • Includes reflection, refraction, diffraction, and interference of light.
• Quantum Mechanics: Describes the behavior of matter at the atomic and subatomic level.
  • Features concepts like quantization, wave-particle duality, and uncertainty principle.
• Nuclear Physics: Focuses on the structure, properties, and reactions of atomic nuclei.
  • Topics include radioactivity, nuclear fission, and nuclear fusion.
• Particle Physics: Studies the fundamental constituents of matter and their interactions.
  • Explores elementary particles, fundamental forces, and the Standard Model.
• Condensed Matter Physics: Examines the physical properties of condensed phases of matter.
  • Including solids and liquids, focusing on phenomena like superconductivity and magnetism.
• Relativity: Studies space, time, gravity, and the motion of objects at high speeds.
  • Comprises special relativity and general relativity.

Fundamental Quantities and Units

• Length: Measured in meters (m).
• Mass: Measured in kilograms (kg).
• Time: Measured in seconds (s).
• Electric Current: Measured in amperes (A).
• Temperature: Measured in kelvins (K).
• Amount of Substance: Measured in moles (mol).
• Luminous Intensity: Measured in candelas (cd).

Motion

• Displacement: Change in position of an object.
• Velocity: Rate of change of displacement with respect to time.
  • Measured in meters per second (m/s).
• Acceleration: Rate of change of velocity with respect to time.
  • Measured in meters per second squared (m/s²).
• Equations of Motion: Describe the motion of an object with constant acceleration.
  • These equations relate displacement, initial velocity, final velocity, acceleration, and time.

Forces

• Newton's First Law: An object at rest stays at rest, and an object in motion stays in motion with the same speed and direction unless acted upon by a force.
• Newton's Second Law: The force acting on an object is equal to the mass of the object multiplied by its acceleration (F = ma).
• Newton's Third Law: For every action, there is an equal and opposite reaction.

Energy

• Kinetic Energy: Energy possessed by an object due to its motion.
  • Equal to one-half of the mass times the square of the velocity (KE = 1/2 mv²).
• Potential Energy: Energy possessed by an object due to its position or condition.
  • Examples: gravitational potential energy (PE = mgh) and elastic potential energy.
• Conservation of Energy: The total energy of an isolated system remains constant.
  • Energy can neither be created nor destroyed, but it can be transformed from one form to another.

Waves

• Transverse Waves: Waves in which the displacement is perpendicular to the direction of propagation.
  • Examples: light waves and water waves.
• Longitudinal Waves: Waves in which the displacement is parallel to the direction of propagation.
  • Example: sound waves.
• Wavelength: Distance between two consecutive points in phase on a wave.
• Frequency: Number of complete oscillations per unit time.
  • Measured in hertz (Hz).
• Amplitude: Maximum displacement of a point on a wave from its equilibrium position.
• Wave Speed: Product of wavelength and frequency (v = λf).
• Interference: Superposition of two or more waves, resulting in either constructive or destructive interference.
• Diffraction: Bending of waves around obstacles or through openings.

Electricity and Magnetism

• Electric Charge: Physical property that causes matter to experience a force when placed in an electromagnetic field.
  • Measured in coulombs (C).
• Electric Field: Region around an electric charge where another charge experiences a force.
• Electric Potential: Electric potential energy per unit charge.
  • Measured in volts (V).
• Electric Current: Rate of flow of electric charge.
  • Measured in amperes (A).
• Resistance: Opposition to the flow of electric current.
  • Measured in ohms (Ω).
• Ohm's Law: Voltage across a conductor is proportional to the current through it (V = IR).
• Magnetic Field: Region around a magnet or current-carrying conductor where a magnetic force is exerted.
• Electromagnetic Induction: Production of an electromotive force (EMF) in a circuit due to a changing magnetic field.

Thermodynamics

• Temperature: Measure of the average kinetic energy of the particles in a system.
• Heat: Transfer of energy between objects or systems due to a temperature difference.
  • Measured in joules (J).
• Specific Heat Capacity: Amount of heat required to raise the temperature of one unit mass of a substance by one degree Celsius.
• First Law of Thermodynamics: Change in internal energy of a system is equal to the heat added to the system minus the work done by the system (ΔU = Q - W).
• Second Law of Thermodynamics: Entropy of an isolated system tends to increase over time.
  • Heat cannot spontaneously flow from a colder body to a hotter body.

Quantum Mechanics

• Quantization: Energy, momentum, and other physical quantities are quantized, meaning they can only take on discrete values.
• Wave-Particle Duality: Particles exhibit both wave-like and particle-like properties.
• Uncertainty Principle: It is impossible to simultaneously know both the position and momentum of a particle with perfect accuracy.
• Superposition: A quantum system can exist in multiple states simultaneously.
• Quantum Entanglement: Two or more particles become linked together in such a way that the state of one particle instantly affects the state of the other, regardless of the distance between them.

Relativity

• Special Relativity: Deals with the relationship between space and time for observers moving at constant velocities.
  • Key concepts include time dilation, length contraction, and the equivalence of mass and energy (E = mc²).
• General Relativity: Deals with gravity as a curvature of spacetime caused by mass and energy.
  • Explains phenomena such as the bending of light around massive objects and the existence of black holes.