Key takeaways
- Eight units across optics, modern physics and semiconductors.
- Key formulas for fringe width, Newton's rings, grating, Malus' and Brewster's laws, de Broglie wavelength and numerical aperture.
- Solved particle-in-a-box example and short worked examples in each unit.
- Ten practice questions at the end, mixing theory and numericals.
- Original Uncodemy revision notes; check your own university syllabus.
About these handwritten notes
These are original Uncodemy revision notes for Engineering Physics, written in a clean handwritten style so they feel like a topper's notebook rather than a textbook. They are short on purpose: each unit gives the key definitions, formulas, a solved example or two and the points that are easy to forget.
The notes follow the common syllabus that most Indian B.Tech universities use for this subject, including universities that follow the AICTE model curriculum. They are not official notes from any university. Unit names, order and depth differ from one university to another, so check your own university syllabus and mark any topic that is missing before you rely on the notes for an exam. Physics papers mix derivations, short theory and numericals, so the notes keep a formula box and a short example for each topic.
What's inside the engineering physics notes
The notes have eight units. One line on each:
Unit 1: Interference
Coherent sources, Young's double slit and fringe width, conditions for bright and dark fringes, interference in thin films, and Newton's rings with the formula for wavelength.
Unit 2: Diffraction
Fresnel and Fraunhofer diffraction, single slit diffraction and the diffraction grating equation (a + b) sin θ = nλ.
Unit 3: Polarisation
Plane polarised light, Malus' law, Brewster's law and double refraction in calcite and quartz.
Unit 4: Quantum mechanics basics
Planck's idea, the photoelectric effect, Compton shift, de Broglie matter waves, Heisenberg's uncertainty principle, the Schrödinger equation and the particle in a 1D box.
Unit 5: Lasers
Stimulated emission, population inversion, metastable states, pumping methods, the optical resonator and ruby and He-Ne lasers (3-level vs 4-level).
Unit 6: Fibre optics
Total internal reflection, critical angle, numerical aperture and acceptance angle, V-number, single mode and multimode fibres, attenuation and dispersion.
Unit 7: Semiconductor basics
Band theory, intrinsic and extrinsic semiconductors, the Fermi level, the mass action law, the Hall effect, the p-n junction, LEDs and solar cells, with a solved particle-in-a-box example.
Unit 8: Most asked questions (practice)
Ten practice questions covering optics, quantum mechanics, lasers, fibres and semiconductors.
How to revise engineering physics with these notes
- Make one formula sheet. Fringe width, Newton's rings, grating, Malus' law, Brewster's law, de Broglie wavelength, energy in a 1D box, numerical aperture and Hall coefficient fit on a single page.
- Learn constants and units. The notes stress h, e, the electron mass and c. Many numericals go wrong because of a unit slip, such as nm against m or eV against J.
- Practise each derivation once by hand. Newton's rings, the de Broglie wavelength for an electron accelerated through V volts and the particle in a box are common long questions. Writing them once makes the exam much easier.
- Draw the diagrams. Newton's rings set-up, energy levels for a laser, the structure of an optical fibre and band diagrams earn marks on their own.
- Use a calculator for numericals. Use the scientific calculator to check powers of ten in quantum and fibre problems.
- Revise in pairs. Interference with diffraction, lasers with fibre optics, and quantum mechanics with semiconductors. Each pair shares ideas.
Exam focus: high-weightage topics
The tip at the end of the notes says that exams very often have a numerical each from fringe width or Newton's rings, de Broglie wavelength, particle in a box and numerical aperture of a fibre. Theory questions usually come from lasers, polarisation and semiconductors.
Topics worth extra time:
- Newton's rings: the set-up and the formula for wavelength.
- Diffraction: Fresnel vs Fraunhofer, and the grating equation.
- Polarisation: Malus' law and Brewster's law with an example.
- Matter waves: de Broglie wavelength for an electron accelerated through V volts.
- Schrödinger equation: solve it for a particle in a 1D box and find the energy levels.
- Lasers: stimulated emission, population inversion and the He-Ne laser.
- Fibre optics: NA and acceptance angle for given n1 and n2; single mode vs multimode fibres and fibre losses.
- Semiconductors: the Hall effect and the position of the Fermi level in intrinsic and extrinsic semiconductors.
Typical questions
The PDF's practice set includes questions such as "Find NA and acceptance angle for n1 = 1.48, n2 = 1.46" and "Explain stimulated emission and population inversion". These are practice questions, not a prediction of your exam.
Who these notes are for
- First-year B.Tech students of all branches taking Engineering Physics in semester 1 or 2.
- Students who need a quick refresher on optics, quantum mechanics or semiconductors before an electronics or communication subject.
- Anyone preparing a formula sheet for physics before the exam.
For unit-wise practice questions with answer outlines, use the Engineering Physics important questions PDF along with these notes.
Common mistakes to avoid
- Mixing up the centre of Newton's rings. In reflected light the centre is dark. Use the right formula for bright and dark rings.
- Wrong grating element. (a + b) = 1/N, where N is lines per unit length. Convert lines per cm to lines per metre if your answer is in metres.
- Forgetting the square in energy levels. In a 1D box, E is proportional to n², so E2 is four times E1.
- Using degrees and radians wrongly. Check calculator mode before finding acceptance angles.
- Mixing up n-type and p-type. Donors (P, As) give n-type; acceptors (B, Al) give p-type. A negative Hall coefficient means electrons are the carriers.
Key formulas to know by heart
Before the exam, check that you can write these from memory:
- Fringe width β = λD/d, and the Newton's rings relation between ring diameter and wavelength.
- Grating equation (a + b) sin θ = nλ and the single slit minima a sin θ = nλ.
- Malus' law I = I0 cos² θ and Brewster's law tan θp = μ.
- de Broglie wavelength λ = h/p, and its form for an electron accelerated through V volts.
- Energy levels in a 1D box, which grow as n².
- Numerical aperture NA = √(n1² - n2²) and the critical angle sin θc = n2/n1.
- The mass action law n p = ni² and the Hall coefficient R_H = 1/(nq).
A simple 4-day revision plan
- Day 1: Units 1 to 3. Interference, diffraction and polarisation, with the optics formulas.
- Day 2: Unit 4. Quantum mechanics, including the particle-in-a-box derivation.
- Day 3: Units 5 to 7. Lasers, fibre optics and semiconductors.
- Day 4: Solve the ten practice questions with a timer and revise your formula sheet.
Download Engineering Physics Handwritten Notes PDF
Engineering Physics Handwritten Notes PDF
The PDF carries the same content as this page in a clean, print-ready layout, so you can read it offline and keep it for revision.
6 pages · 273 KB · PDF · Updated 5 Nov 2026