JEE Main Modern Physics: Complete Guide to Photoelectric Effect, Atoms & Nuclei
Modern Physics is a reliable 3-4 question block in JEE Main. It is self-contained (does not require knowledge of classical mechanics to solve) and highly formulaic — making it one of the best chapters to master for guaranteed marks.
Photoelectric Effect (1-2 questions)
Einstein's photoelectric equation: KE = hν - φ (work function). Key: stopping potential, threshold frequency, photocurrent dependence on intensity vs frequency. JEE Main: Given threshold wavelength, find stopping potential for another wavelength.
de Broglie Wavelength
λ = h/mv = h/√(2mKE). For an electron accelerated through voltage V: λ = 12.27/√V Å. JEE Main often compares wavelengths of electrons, protons, and photons with equal energy or momentum.
Bohr's Atomic Model (1 question)
Quantization condition, energy levels (En = -13.6/n² eV for hydrogen), spectral series (Lyman, Balmer, Paschen). Standard question: Find wavelength of transition from n=4 to n=2 (Balmer series). Know Rydberg constant = 1.097 × 10⁷ m⁻¹.
Nuclear Physics (1 question)
Binding energy, mass defect, nuclear reactions. Radioactive decay: N = N₀e^(-λt), half-life T½ = 0.693/λ. Q-value of nuclear reactions. Common JEE Main question: after 3 half-lives, what fraction remains? (Answer: 1/8).
Semiconductors (1 question)
p-n junction, forward/reverse bias, diode characteristics, transistor action (CE configuration, β = Ic/Ib). Logic gates (AND, OR, NOT, NAND, NOR — truth tables). This is almost entirely factual and NCERT-based.
Ready to Test Your Knowledge?
Practice with real exam-pattern questions. Track your weak topics. Get instant results.
Practice Modern Physics PYQsExplore More on TestVeda
Related Articles
How to Prepare for JEE Main from Zero
Starting JEE Main preparation can feel overwhelming, but with the right strategy anyone ca…
JEE Main Physics: Most Important Topics and Weightage
Physics is often the deciding subject in JEE Main. Knowing which chapters carry the most m…
JEE Main Chemistry: Chapter-wise Weightage and Important Topics
Chemistry is the most scoring subject in JEE Main if you approach it right. With strong NC…
JEE Main Mathematics: Most Important Topics and Scoring Strategy
Mathematics in JEE Main tests speed and accuracy. With 25 questions in 60 minutes, you nee…