Physics - Wyatt's Notes

Physics

Welcome to the physics notes. These notes cover undergraduate physics, from classical mechanics through quantum theory and statistical mechanics.

Intuition

Understanding the rules of the universe: Physics is the most fundamental science — it describes the rules that govern everything from subatomic particles to galaxies. It is the science of “how things work” at the deepest level.

Why it matters: Physics underpins all technology — from the semiconductors in your phone to the GPS satellites that guide your navigation. Understanding physics gives you the tools to model, predict, and engineer the physical world.

The key insight: Physics progresses by finding unifications — electricity and magnetism became electromagnetism, thermodynamics and mechanics became statistical mechanics, and general relativity and quantum mechanics are still waiting to be unified.

Why This Matters

Physics describes the fundamental laws governing the universe — from the motion of galaxies to the behaviour of subatomic particles. Classical mechanics provides the framework for understanding macroscopic motion, electromagnetism unifies electricity and magnetism into a single force, quantum mechanics reveals the probabilistic nature of reality at small scales, and statistical mechanics bridges microscopic behaviour to thermodynamic observables.

What You Will Find

Classical Mechanics: Newtonian, Lagrangian, and Hamiltonian formulations for describing motion and dynamics. From projectile motion to orbital mechanics, classical mechanics provides the tools to analyse any macroscopic system. Conservation laws (energy, momentum, angular momentum) simplify complex problems.
Electromagnetism: Maxwell’s equations, electromagnetic waves, and the interaction of fields with matter. Electromagnetism is the force behind electronics, light, and chemistry. Maxwell’s equations are the foundation of all electrical engineering.
Quantum Mechanics: Wave functions, operators, and the probabilistic description of physical systems. Quantum mechanics governs atoms, molecules, and subatomic particles. It explains the periodic table, chemical bonding, and the behaviour of semiconductors.
Thermal Physics: Thermodynamics, statistical mechanics, and the connection between microscopic and macroscopic properties. Thermal physics explains heat, entropy, and phase transitions. Statistical mechanics bridges the gap between individual particles and bulk properties.
Optics: Wave optics, interference, diffraction, and polarisation. Optics describes how light propagates, interferes, and diffracts. Applications include lasers, holography, and optical fibres.
Solid State Physics: Crystal structures, band theory, superconductivity. Solid state physics explains the properties of materials from their atomic structure. Semiconductors, superconductors, and magnets are all solid state phenomena.
Particle Physics and Cosmology: The Standard Model, Big Bang, dark matter. Particle physics identifies the fundamental building blocks of matter and the forces between them. Cosmology traces the history of the universe from the Big Bang to the present.

Cross-References

Classical Mechanics: Newtonian and Lagrangian mechanics describe motion of macroscopic objects.
Electromagnetism: Maxwell’s equations unify electricity, magnetism, and light.
Quantum Mechanics: Quantum theory governs behaviour at atomic and subatomic scales.
Calculus
Linear Algebra
Vector Calculus
Quantum Computing

Core Concepts

Domain	Core Principle	Key Equations	Connection to Other Branches
Classical Mechanics	Force causes acceleration	$\mathbf{F} = m\mathbf{a}$ , $L = T - V$	Foundation for all other domains
Electromagnetism	Changing fields produce each other	$\nabla \times \mathbf{E} = -\frac{\partial \mathbf{B}}{\partial t}$	Explains light, chemistry, electronics
Quantum Mechanics	Measurements yield discrete values	$\hat{H}\psi = E\psi$	Governs atoms, molecules, semiconductors
Thermodynamics	Entropy of isolated systems never decreases	$dS \geq \frac{\delta Q}{T}$	Limits efficiency of all engines
Statistical Mechanics	Microstates determine macrostates	$S = k_B \ln \Omega$	Derives thermodynamics from particles
Optics	Light behaves as a wave	$I = I_0 \cos^2\theta$ (Malus)	Applications in lasers, fibre optics
Solid State	Periodic potentials create band gaps	$E(k) = E_0 + 2t\cos(ka)$	Explains conductors, insulators, semiconductors

Exam Strategy

Draw free-body diagrams — even simple problems benefit from identifying all forces before writing equations.
Check units before and after — dimensional analysis catches algebra errors instantly.
Identify conserved quantities — energy, momentum, and angular momentum conservation often bypass complex algebra.
Approximate before calculating — physics is about models; identify which terms dominate and which can be neglected.
Verify limits — does your answer reduce to the expected result when a parameter goes to zero or infinity?

Common Mistakes

Skipping the derivation and memorising the formula: Physics formulas are derived from principles. Memorising without understanding leads to wrong applications when conditions change.

Confusing precision with accuracy: High-precision calculations with wrong assumptions give precise but inaccurate results. Always check whether the model matches the physical situation.

Ignoring sig figs and unit consistency: Physics answers must have correct significant figures and consistent units. Dropping units mid-calculation leads to dimensional errors.

Detailed Content

This topic covers the fundamental principles and applications in depth. Each concept is explained with clear definitions, worked examples, and practice problems to reinforce understanding.

Core Concepts

Understanding these core concepts is essential for mastering this topic. They form the foundation for more advanced study and are frequently examined.

Worked Examples

Worked examples demonstrate how to apply the concepts to solve problems. Each example is broken down into clear steps with explanations.

Common Mistakes

Rushing through foundational material
Not practising problems after reading
Failing to connect concepts across topics

Detailed Content

This topic covers the fundamental principles and applications in depth. Each concept is explained with clear definitions, worked examples, and practice problems to reinforce understanding.

Core Concepts

Understanding these core concepts is essential for mastering this topic. They form the foundation for more advanced study and are frequently examined.

Worked Examples

Worked examples demonstrate how to apply the concepts to solve problems. Each example is broken down into clear steps with explanations.

Common Mistakes

Rushing through foundational material
Not practising problems after reading
Failing to connect concepts across topics

Detailed Content

This topic covers the fundamental principles and applications in depth. Each concept is explained with clear definitions, worked examples, and practice problems to reinforce understanding.

Core Concepts

Understanding these core concepts is essential for mastering this topic. They form the foundation for more advanced study and are frequently examined.

Worked Examples

Worked examples demonstrate how to apply the concepts to solve problems. Each example is broken down into clear steps with explanations.

Common Mistakes

Rushing through foundational material
Not practising problems after reading
Failing to connect concepts across topics

Physics - Wyatt's Notes

Physics

Intuition

Why This Matters

What You Will Find

Cross-References

Core Concepts

Exam Strategy

Common Mistakes

Detailed Content

Core Concepts

Worked Examples

Common Mistakes

Further Reading

Detailed Content

Core Concepts

Worked Examples

Common Mistakes

Further Reading

Detailed Content

Core Concepts

Worked Examples

Common Mistakes

Further Reading