JEE Main · Physics — Modern Physics · Tamil Nadu, India

Physics — Modern Physics for the JEE Main Exam — Tamil Nadu candidates

5% of the JEE Main test plan. Photoelectric effect, nuclear physics, atomic models, dual nature of matter, and semiconductors — about 15% of JEE Physics. Calibrated for Tamil candidates.

If you have already studied this content from a textbook, you know the material. The question this page answers is whether you can apply it under exam conditions. Physics — Modern Physics sits at roughly 5% of the Joint Entrance Examination Main content distribution — Modern Physics is the most formula-dense topic in JEE Physics and the area where students recover marks lost in mechanics and E&M. Photoelectric effect and nuclear decay are almost guaranteed to appear in JEE Main. JEE Advanced includes Bohr model derivations and semiconductor band theory. Pass rates for the JEE Main are published annually by the awarding body and vary by cohort and locale. For Tamil Nadu candidates preparing for JEE Main, the calibration of study to local context matters: Tamil Nadu uses 7.5% NEET government-school reservation and runs separate state-quota counselling. JEE Main and GATE candidate volumes are second only to Maharashtra.

Pass rates for JEE Main (Tamil Nadu, India) are published periodically by the awarding body.

Common failure modes

These are the patterns that cause most candidates to lose marks on this topic. Recognising them in advance is half the work.

!Confusing threshold frequency with work function (φ = hν₀, not hν₀/e)
!Applying Einstein's photoelectric equation without subtracting the work function
!Misidentifying the nuclear binding energy trend — iron-56 is the most stable, not the lightest or heaviest nucleus
!Forgetting de Broglie wavelength depends on momentum, not speed, when the particle is relativistic
!Mixing up NPN and PNP transistor biasing configurations

Study tips

1Memorise Planck's constant (h = 6.626 × 10⁻³⁴ J·s) and the eV–joule conversion (1 eV = 1.6 × 10⁻¹⁹ J) — both are used in almost every modern-physics calculation.
2Drill Bohr model energy levels for hydrogen: Eₙ = −13.6/n² eV. JEE Main frequently asks about energy transitions.
3Practice half-life problems with the formula N(t) = N₀(1/2)^(t/T½) — variants appear every year.
4For semiconductors, understand intrinsic vs extrinsic (n-type, p-type) and the forward-bias vs reverse-bias I-V curve.
5Work through at least one paper-year of photoelectric problems to internalise the Einstein equation and the stopping-potential concept.
6NEET-UG is offered in Tamil (தமிழ்) at all TN centres. Many state-board students prefer Tamil-medium for biology questions but English-medium for physics and chemistry — you must choose one medium for the entire paper.
7For TN MBBS admission: register on TN Health website for the 7.5% government-school reservation if eligible — separate from MCC counselling.
8GATE Chennai and Coimbatore centres fill fastest; submit your GATE application within 72 hours of opening to secure your preferred centre.

Sample JEE Main Physics — Modern Physics questions

These sample items mirror the format and difficulty of real JEE Main questions. Practice with thousands more on the free Koydo question bank.

1
In the photoelectric effect, the stopping potential depends on:
- AIntensity of incident light only
- BFrequency of incident light onlyCorrect
- CBoth intensity and frequency
- DNeither intensity nor frequency
Why this answer?
Illustrative JEE-style: Einstein's photoelectric equation gives KE_max = hν − φ = eV_stop. The stopping potential V_stop depends only on the frequency ν of the incident light, not on its intensity. Higher intensity increases the number of photoelectrons but not their maximum energy.
2
A radioactive sample has a half-life of 5 years. After 15 years, the fraction remaining is:
- A1/8Correct
- B1/4
- C1/3
- D1/16
Why this answer?
Illustrative JEE-style: 15 years = 3 half-lives. The fraction remaining = (1/2)³ = 1/8.
3
The de Broglie wavelength of an electron accelerated through a potential difference V is proportional to:
- AV
- B1/√VCorrect
- C√V
- D1/V
Why this answer?
Illustrative JEE-style: KE = eV, so momentum p = √(2meV). de Broglie wavelength λ = h/p = h/√(2meV) ∝ 1/√V.

Frequently asked questions

How many marks does Modern Physics typically carry in JEE Main?

Approximately 12–16 marks out of 100 in Physics (3–4 questions at 4 marks each). The exact allocation varies by year, but photoelectric effect and nuclear physics appear in virtually every paper.

Is semiconductors a reliable scoring topic?

Yes. Semiconductor questions (p-n junction, transistor, logic gates) are formulaic and JEE Main tests them predictably. One or two questions on semiconductors can usually be solved in under 2 minutes each.

What is the JEE Main pass rate for Tamil candidates?

Pass rates for JEE Main candidates in Tamil Nadu, India are published periodically by the awarding body. Practice questions, full-length simulations, and weak-area drills are the highest-impact way to improve your odds.

How long should Tamil candidates study Physics — Modern Physics for the JEE Main?

For most candidates, focused mastery of Physics — Modern Physics requires 20–40 hours of deliberate practice — drilling sample questions, reviewing failure modes, and timing yourself against exam conditions. Tamil Nadu uses 7.5% NEET government-school reservation and runs separate state-quota counselling. JEE Main and GATE candidate volumes are second only to Maharashtra. Combine Physics — Modern Physics study with full-length mock exams in the final two weeks before your test date.

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Related study guides

Regulatory citation: NTA JEE Main Information Bulletin — Physics syllabus (Dual Nature of Radiation and Matter, Atoms, Nuclei, Electronic Devices).