Key Concepts in Physics

Branches of Physics
- Classical Mechanics: Study of motion, forces, energy, and systems.
- Electromagnetism: Interaction of electric charges, magnetic fields, and electromagnetic forces.
- Thermodynamics: Laws governing heat, energy, and work.
- Quantum Mechanics: Behavior of particles at atomic and subatomic levels.
- Relativity: Effects of gravity and motion on time and space, introduced by Einstein.
Fundamental Laws
- Newton's Laws of Motion:
  1. An object at rest stays at rest; an object in motion stays in motion unless acted upon by a force.
  2. F = ma (Force equals mass times acceleration).
  3. For every action, there is an equal and opposite reaction.
- Conservation Laws:
  - Conservation of Energy: Energy cannot be created or destroyed, only transformed.
  - Conservation of Momentum: Total momentum remains constant in an isolated system.
Key Terms
- Force: An interaction that causes an object to change velocity.
- Energy: The capacity to do work, types include kinetic and potential.
- Work: Work is done when a force acts on an object over a distance (W = Fd).
- Power: The rate of doing work or transferring energy (P = W/t).
Motion
- Types of Motion:
  - Linear: Straight-line movement.
  - Rotational: Movement around an axis.
  - Oscillatory: Back-and-forth motion (e.g., pendulums).
- Kinematics: Describes motion without considering its causes.
- Dynamics: Examines the forces that cause motion.
Waves and Sound
- Wave Properties: Wavelength, frequency, amplitude, speed.
- Types of Waves:
  - Mechanical: Require a medium (e.g., sound waves).
  - Electromagnetic: Do not require a medium (e.g., light waves).
- Sound: A mechanical wave produced by vibrating objects, travels through a medium.
Light and Optics
- Nature of Light: Electromagnetic radiation that behaves as both a wave and a particle (photon).
- Reflection and Refraction: Bending of light when passing through different media.
- Lenses: Converging (convex) and diverging (concave) lenses manipulate light paths.
Electricity and Magnetism
- Electric Charge: Fundamental property of matter, exists in positive and negative forms.
- Ohm's Law: V = IR (Voltage equals current times resistance).
- Magnetic Fields: Produced by moving electric charges, affecting other moving charges.
Modern Physics
- Quantum Theory: Discrete energy levels, wave-particle duality, uncertainty principle.
- Nuclear Physics: Study of atomic nuclei, radioactivity, and nuclear reactions.
- Particle Physics: Fundamental particles (quarks, leptons) and their interactions.
Measurement and Units
- SI Units: Standardized units for measurement (e.g., meter, kilogram, second).
- Dimensional Analysis: Technique to convert between units and check equations.
Applications of Physics
- Engineering: Utilizing physical principles in design and construction.
- Medicine: Imaging technologies (e.g., MRI, X-rays) and radiation therapeutics.
- Environmental Science: Understanding natural phenomena and energy systems.

Branches of Physics

Classical Mechanics: Involves the study of motion, forces, energy, and the behavior of physical systems.
Electromagnetism: Focuses on the interactions between electric charges and magnetic fields, including electromagnetic forces.
Thermodynamics: Governs the principles of heat transfer, energy conversion, and mechanical work.
Quantum Mechanics: Explores the behavior of matter and energy at atomic and subatomic levels, introducing concepts like quantization and wave functions.
Relativity: Examines the relationship between gravity, motion, time, and space, popularized by Einstein's theories.

Fundamental Laws

Newton's Laws of Motion:
- An object will remain at rest or in uniform motion unless acted upon by an external force.
- Force is defined by the equation F = ma (mass times acceleration).
- For every action, there is an equal and opposite reaction.
Conservation Laws:
- Conservation of Energy: Energy can neither be created nor destroyed, only converted from one form to another.
- Conservation of Momentum: In an isolated system, the total momentum remains constant unless external forces act upon it.

Key Terms

Force: Causes an object to accelerate or change velocity.
Energy: The ability to perform work; categorized into kinetic (motion) and potential (stored) energy.
Work: Calculated by the formula W = Fd, where force acts over a distance.
Power: The rate at which work is performed, expressed as P = W/t.

Motion

Types of Motion:
- Linear Motion: Movement in a straight line.
- Rotational Motion: Movement around an axis.
- Oscillatory Motion: Repeated back-and-forth motion, such as that of a pendulum.
Kinematics: Describes motion using parameters like displacement, velocity, and acceleration without addressing the forces.
Dynamics: Analyzes the forces that cause motion and the resulting effects.

Waves and Sound

Wave Properties: Key characteristics include wavelength, frequency, amplitude, and speed.
Types of Waves:
- Mechanical Waves: Require a medium for propagation (e.g., sound waves).
- Electromagnetic Waves: Can travel through a vacuum (e.g., light waves).
Sound: A mechanical wave resulting from vibrating objects; travels through air or other media.

Light and Optics

Nature of Light: Exhibits dual characteristics of waves and particles (photons), comprising electromagnetic radiation.
Reflection and Refraction: Light changes direction when it encounters different media, causing bending.
Lenses:
- Converging (Convex) Lenses: Focus light rays to a point.
- Diverging (Concave) Lenses: Spread light rays apart.

Electricity and Magnetism

Electric Charge: A fundamental property of matter, existing in positive and negative forms; is the source of electromagnetic interactions.
Ohm's Law: Defines the relationship between voltage (V), current (I), and resistance (R), expressed as V = IR.
Magnetic Fields: Generated by moving electric charges and can exert forces on other charges.

Modern Physics

Quantum Theory: Describes physical phenomena at very small scales, emphasizing discrete energy levels and wave-particle duality.
Nuclear Physics: Focuses on the properties and behaviors of atomic nuclei, including radioactivity and nuclear reactions.
Particle Physics: Studies fundamental particles like quarks and leptons and the fundamental forces influencing their interactions.

Measurement and Units

SI Units: Internationally recognized units for measuring physical quantities such as length (meter), mass (kilogram), and time (second).
Dimensional Analysis: A method used for converting between units and verifying the correctness of equations.

Applications of Physics

Engineering: Applies principles of physics in the design and construction of structures and machinery.
Medicine: Utilizes imaging technologies (e.g., MRI and X-rays) and radiation therapies for diagnosis and treatment.
Environmental Science: Aids in understanding physical phenomena and energy systems to address environmental challenges.