Modern Physics for NEET: Chapter Map and a Revision Plan
Modern physics for NEET is the name students and teachers give to three units of the official NEET (UG) Physics syllabus: Unit 17, Dual Nature of Matter and Radiation, Unit 18, Atoms and Nuclei, and Unit 19, Electronic Devices. They are taught in four NCERT Class 12 Physics chapters, numbered 11 to 14. This guide matches every syllabus line to the chapter that teaches it, shows the six Unit 19 topics the current NCERT book does not cover, lists the numbers NCERT prints, and ends with a revision order you can start this week.
What is modern physics for NEET, and which chapters does it cover?
Modern physics is the physics of the very small: light behaving as particles, electrons behaving as waves, the structure of the atom and its nucleus, and the semiconductors inside every phone. The official NEET (UG) 2026 syllabus, which the National Medical Commission's Undergraduate Medical Education Board finalised on 22 December 2025, never uses the phrase "modern physics". It simply lists 20 Physics units. Units 17, 18 and 19 are the ones everyone means by modern physics for NEET.
All three live in NCERT Class 12 Physics Part II:
- Chapter 11, Dual Nature of Radiation and Matter for Unit 17 (Reprint 2026-27).
- Chapter 12, Atoms and Chapter 13, Nuclei for Unit 18 (both Reprint 2026-27).
- Chapter 14, Semiconductor Electronics: Materials, Devices and Simple Circuits for Unit 19 (the online PDF is marked Reprint 2025-26).
Why care about the exact mapping? The NEET (UG) 2026 Information Bulletin gives Physics 45 of the 180 questions and 180 of the 720 marks, and every wrong answer costs a mark. NTA does not publish chapter-wise weightage, so nobody can honestly promise you a number of modern physics questions. What you can control is whether every line of these three units is covered before you sit a mock.
How does each syllabus line map to an NCERT chapter?
Here is the syllabus text for Units 17 to 19, split into phrases, with the NCERT section that teaches each one. The last column is where the two documents part ways.
| Syllabus phrase | NCERT section | Covered in the current book? |
|---|---|---|
| Dual nature of radiation, photoelectric effect | Ch 11, sections 11.2 to 11.5 | Yes |
| Hertz and Lenard's observations | Ch 11, 11.3.1 and 11.3.2 | Yes (Hertz 1887; Hallwachs and Lenard 1886 to 1902) |
| Einstein's photoelectric equation, particle nature of light | Ch 11, 11.6 and 11.7 | Yes |
| Matter waves, de Broglie relation | Ch 11, 11.8 | Yes, λ = h/p |
| Alpha-particle scattering, Rutherford's model | Ch 12, 12.2 | Yes (Geiger and Marsden, 1911) |
| Bohr model, energy levels, hydrogen spectrum | Ch 12, 12.3 to 12.6 | Yes |
| Composition and size of nucleus, atomic masses | Ch 13, 13.2 and 13.3 | Yes |
| Mass-energy relation, mass defect, binding energy per nucleon | Ch 13, 13.4 | Yes |
| Nuclear fission and fusion | Ch 13, 13.7 | Yes |
| Semiconductors | Ch 14, 14.2 to 14.4 | Yes |
| Semiconductor diode, I-V in forward and reverse bias | Ch 14, 14.5 and 14.6 | Yes |
| Diode as a rectifier | Ch 14, 14.7 | Yes |
| I-V characteristics of LED, photodiode, solar cell | None | No |
| Zener diode, Zener diode as a voltage regulator | None | No |
| Logic gates (OR, AND, NOT, NAND and NOR) | None | No |
For modern physics for NEET, Units 17 and 18 line up almost perfectly with the book. Unit 19 does not. If you study modern physics for NEET only from the current NCERT chapter, you finish with a third of Unit 19 untouched.
Which Unit 19 topics are missing from the current NCERT book?
Six of the nine items in the Unit 19 syllabus line are not in the NCERT Chapter 14 PDF that NCERT serves today. We searched the full text of that chapter for each term on 18 October 2026: it contains no section on the light emitting diode, the photodiode, the solar cell, the Zener diode or logic gates. The chapter now runs from the classification of metals, conductors and semiconductors to the p-n junction, the diode under forward and reverse bias, and the diode as a half-wave and full-wave rectifier, and stops there.
What does this mean for you? Two things. First, the syllabus is the document that decides what NEET may ask, not the textbook, so these six topics stay on your list. Second, you need a second source for them. A good reference book, your school teacher or your coaching notes all work; our list of best books for NEET 2027 is a place to start. Keep this part short and concrete: the I-V curve of each special diode, how a Zener holds a steady voltage in reverse breakdown, and the truth table of each of the five gates.
There is a gap the other way too. NCERT Chapter 13 has a short section 13.6 on radioactivity (alpha, beta and gamma decay, discovered by Becquerel in 1896), yet the Unit 18 syllabus line names no radioactivity at all. It is a short, descriptive section. Read it once, because it explains where alpha particles come from, but do not spend a week on decay laws that the 2026 syllabus does not list. Our NEET physics formula sheet makes the same call for its formula list, and our guide to the NEET 2027 deleted syllabus is where we will flag it first if the 2027 syllabus changes these units.
What does Chapter 11 really test about the photoelectric effect?
Chapter 11 is short and very rule-based, which makes it one of the friendlier parts of modern physics for NEET. Almost every question tests one of five statements from the NCERT summary:
- Work function is the minimum energy an electron needs to leave a metal surface. NCERT's worked example uses caesium at 2.14 eV.
- Photocurrent depends on the intensity of light, the potential between the plates and the emitter material.
- Stopping potential depends on the frequency of light and the emitter, and for a given frequency it does not depend on intensity. eV₀ = Kmax.
- Threshold frequency: below ν₀ no electrons come out, however bright the light.
- Einstein's equation: Kmax = hν minus φ₀, which is h(ν minus ν₀). Millikan's measurements confirmed it and gave an accurate value of Planck's constant.
The de Broglie part adds one line, λ = h/p, and the idea that matter, not just light, has a dual nature. Most numerical questions are a two-step chain: find the photon energy from the wavelength, subtract the work function, then convert to a speed, a stopping potential or a wavelength. Practise the unit conversion between joules and electron volts until it is automatic, because that is where most modern physics for NEET marks leak.
Which atom and nucleus numbers does NCERT print?
In modern physics for NEET, Chapters 12 and 13 reward exact recall. Every figure below is printed in the current NCERT text, and each one turns into an option sooner or later.
| Fact | Value in NCERT | Chapter |
|---|---|---|
| Ground state energy of hydrogen | minus 13.6 eV (so ionisation energy is 13.6 eV) | 12 |
| Energy of level n | En = minus 13.6/n² eV | 12 |
| Radius of the first Bohr orbit | 5.3 × 10^-11 m | 12 |
| Bohr's second postulate | L = nh/2π, explained by de Broglie in 1923 | 12 |
| Wave nature of electrons confirmed | Davisson and Germer, 1927 | 12 |
| Nuclear radius | R = R₀A^(1/3), with R₀ = 1.2 fm | 13 |
| Nuclear density | About 2.3 × 10^17 kg per cubic metre, the same for all nuclei | 13 |
| 1 atomic mass unit | 931.5 MeV | 13 |
| Binding energy per nucleon | Nearly constant at about 8.0 MeV between A = 30 and A = 170; maximum about 8.75 MeV at A = 56 | 13 |
| Energy scale | 1 kg of uranium by fission about 10^14 J, against about 10^7 J from 1 kg of coal | 13 |
| Band gap | About 0.72 eV for germanium and 1.1 eV for silicon | 14 |
The binding energy curve deserves a second look. It explains both fission and fusion in one picture: heavy nuclei beyond A = 170 and light nuclei below A = 30 sit lower on the curve, so splitting the first or joining the second moves the products towards the 8 MeV plateau and releases energy. If you can sketch that curve from memory, three or four question types become easy.
Why does Chemistry Unit 2 make modern physics count twice?
Because the two syllabuses overlap. Chemistry Unit 2, Atomic Structure, lists the photoelectric effect, the spectrum of the hydrogen atom, the Bohr model with its energy and radius relations, the limitations of Bohr's model and de Broglie's relationship. That is most of Units 17 and 18 again, taught from a chemist's angle in NCERT Class 11 Chemistry, Unit 2, Structure of Atom.
Use it. Study the Physics chapters first for the derivations and the numerical style, then read the Chemistry unit for its extras: it names the Lyman, Balmer and Paschen series in a table, and adds Heisenberg's uncertainty principle and atomic orbitals as one-electron wave functions, neither of which the Physics chapters teach. One topic, two sections of the paper, which makes modern physics for NEET better value than its three units suggest. Our breakdown of NEET Chemistry questions shows where Atomic Structure sits among the 20 Chemistry units.
How should you revise modern physics for NEET, step by step?
This order for modern physics for NEET works for Class 12 students meeting these chapters for the first time and for droppers on a second pass.
- Read Chapters 11 to 14 once, in order. Skip nothing on the first read. Our guide on [how to study NCERT for NEET](/blogs/how-to-study-ncert-for-neet-2027/) explains how to read for detail on the second pass.
- Write the five photoelectric rules and the Bohr relations on one page. Then do the NCERT exercises at the end of Chapters 11 and 12 without looking.
- Draw three graphs from memory. Photocurrent against collector potential, stopping potential against frequency, and binding energy per nucleon against mass number. Each one carries a whole question type.
- Close the Unit 19 gap in one sitting. From a second source, learn LED, photodiode and solar cell I-V curves, the Zener regulator and the five gate truth tables. Put each truth table on a card in your [NEET flashcards](/blogs/neet-flashcards/) deck.
- Read Chemistry Unit 2 the same week. Mark the lines that repeat Physics and the ones that add something new.
- Test under time. Use [NEET previous year question papers](/blogs/neet-2027-previous-year-question-papers/) and the [NTA mock test](/blogs/nta-mock-test-for-neet-2027/), then sort every wrong answer by chapter and by type: concept, formula or calculation.
For the full Physics picture, our NEET Physics questions guide explains how all 45 questions are marked, and the NEET 2027 Physics preparation strategy places modern physics for NEET in a year-long plan. If you want the whole three-subject syllabus in one view, futureMBBS keeps a clear NEET syllabus overview. Its guide to time management in the NEET exam helps you decide when to attempt these quicker Physics questions, and its plan for starting NEET UG 2027 preparation shows where this unit fits in the months ahead.
Five traps in modern physics for NEET questions
- Thinking brighter light means faster electrons. Intensity changes the photocurrent, not the stopping potential. Only frequency changes Kmax.
- Dropping the minus sign. Hydrogen energy levels are negative. The ionisation energy is plus 13.6 eV, the ground state is minus 13.6 eV.
- Mixing nuclear radius and density. Radius grows as A to the power one third, but density stays the same for every nucleus.
- Studying only the NCERT chapter for Unit 19. Six syllabus items are not in it. Check the syllabus line, not the chapter list.
- Guessing on a half-worked numerical. A wrong answer costs one mark. Our page on NEET negative marking shows when a blank is the better choice.
Want to know whether photoelectric numericals or logic gates are costing you marks? NEETsheet is our NEET UG prep app, with NCERT-aligned question sets and timed mocks that show exactly where Physics slips.
Sources
Every syllabus line, chapter section and number above comes from these official documents, opened and read on 18 October 2026.
- National Medical Commission, Undergraduate Medical Education Board, "Syllabus for NEET (UG) 2026", 22 December 2025, circulated by NTA (Physics Units 17 to 19; Chemistry Unit 2): https://nta.ac.in/Download/Notice/Notice_20260108180635.pdf
- National Testing Agency, Information Bulletin NEET (UG) 2026 (pattern: Physics 45 questions and 180 marks of 720; plus four and minus one marking): https://cdnbbsr.s3waas.gov.in/s37bc1ec1d9c3426357e69acd5bf320061/uploads/2026/02/202602231394640855.pdf
- NCERT, Physics Part II, Class 12, Chapter 11 "Dual Nature of Radiation and Matter" (Reprint 2026-27): https://ncert.nic.in/textbook/pdf/leph203.pdf
- NCERT, Physics Part II, Class 12, Chapter 12 "Atoms" (Reprint 2026-27): https://ncert.nic.in/textbook/pdf/leph204.pdf
- NCERT, Physics Part II, Class 12, Chapter 13 "Nuclei" (Reprint 2026-27): https://ncert.nic.in/textbook/pdf/leph205.pdf
- NCERT, Physics Part II, Class 12, Chapter 14 "Semiconductor Electronics: Materials, Devices and Simple Circuits" (Reprint 2025-26): https://ncert.nic.in/textbook/pdf/leph206.pdf
- NCERT, Chemistry Part I, Class 11, Unit 2 "Structure of Atom" (Reprint 2026-27): https://ncert.nic.in/textbook/pdf/kech102.pdf
- NCERT, online textbooks index: https://ncert.nic.in/textbook.php
- National Testing Agency, notice board archive, checked on 18 October 2026 for any NEET (UG) 2027 notice: https://nta.ac.in/NoticeBoardArchive
Frequently Asked Questions
Modern physics for NEET covers syllabus Units 17, 18 and 19, taught in four NCERT Class 12 Physics chapters: Chapter 11, Dual Nature of Radiation and Matter; Chapter 12, Atoms; Chapter 13, Nuclei; and Chapter 14, Semiconductor Electronics. Optics, Unit 16, is a separate unit.
Yes. Unit 19 of the NEET (UG) 2026 syllabus names logic gates OR, AND, NOT, NAND and NOR, along with the Zener diode, LED, photodiode and solar cell. The current NCERT Chapter 14 does not teach these topics, so study them from a reference book or your teacher's notes.
The Unit 18 syllabus line for 2026 names alpha scattering, the Rutherford and Bohr models, the hydrogen spectrum, nuclear size, mass defect, binding energy, fission and fusion, but not radioactivity. NCERT Chapter 13 still has a short descriptive section on it, which is worth one careful read.
NTA does not publish a chapter-wise question count, so no official number exists. What is fixed is that Physics has 45 questions worth 180 of the 720 marks, with plus four for a right answer and minus one for a wrong one. Any modern physics count you see online comes from unofficial paper analyses.
For Units 17 and 18, almost entirely yes: every syllabus line is taught in Chapters 11, 12 and 13. For Unit 19, no. Six of its nine items, including the Zener diode and logic gates, are missing from the current Chapter 14, so you need one extra source for them.
If you are revising modern physics for NEET alongside the rest of Physics, NEETsheet is our app for practice questions and full-length mocks: neetsheet.in.
