NEET Ray Optics PYQ Patterns (2018–2024)
Most Tested Topic: Mirror/Lens Formula + Sign Convention (2018, 2020, 2021, 2023) Every year, NEET includes at least one direct mirror or lens formula calculation. The numerical involves applying 1/v + 1/u = 1/f (mirror) or 1/v − 1/u = 1/f (lens) with a correctly signed u and f. The question then asks for v, m, or image nature. Strategy: Write down u and f with signs before substituting. Check: is v positive or negative? Does it match the expected image nature for the given object position?
Second Most Tested: TIR and Critical Angle (2019, 2022, 2024) Typical forms: (a) "Find the critical angle for glass (n=1.5)/diamond (n=2.42) in air." (b) "Will TIR occur at angle θ?" (c) "Is TIR possible when light goes from medium A to medium B?" Strategy: Compute θ_c = arcsin(n_rarer/n_denser) and compare with the given angle. Always verify the denser-to-rarer direction first.
Third: Prism Minimum Deviation (2021, 2024) Formula: n = sin((A + δ_m)/2)/sin(A/2). Common: n = 1.5, A = 60° → δ_m ≈ 37.2°. Also: n = √3, A = 60° → δ_m = 60°. Strategy: Never use δ = (n − 1)A unless A is confirmed small (< 10°).
Fourth: Power and Lens Combination (2020, 2022, 2023) P = 1/f (convert to metres first). Combination: P = + . Eye correction: Myopia → concave (P < 0); Hypermetropia → convex (P > 0).
Fifth: Optical Instruments — Microscope and Telescope (2019, 2021, 2023) Telescope M = −f_o/f_e, L = f_o + f_e. Microscope: objective has short f. Common trap: confusing which instrument has the longer-focal-length objective.
Time allocation: 3–4 questions from ray optics in NEET, each worth 4 marks. Invest 3 minutes maximum per question; skip if sign convention is unclear and return later.