NEET Question Patterns (2018–2024)

Pattern 1 — EM Spectrum Application Matching (Most Frequent)

• "Which EM wave is used for...?" — radar, microwave oven, sterilisation, LASIK, night vision, cancer treatment, medical imaging
• Strategy: Memorise the application-to-wave-type mapping completely. Two traps: (i) UV not gamma for sterilisation; (ii) IR not UV for physiotherapy.

Pattern 2 — Displacement Current (NEET 2019 confirmed)

• Definition of displacement current, its formula, and whether it is real charge flow
• Common trap: "displacement current flows due to electron flow in capacitor gap" — WRONG
• Strategy: Id = ε_{0}(dΦ_E/dt); no charge flow; equals conduction current in wire; produces B field.

Pattern 3 — Properties of EM Waves (NEET 2022 confirmed)

• Transverse nature, E perpendicular to B, E and B in phase, $E_{0}$/$B_{0}$ = c
• Common trap: "E and B are 90° out of phase" — WRONG (spatially perpendicular but temporally in phase)
• Strategy: In phase = peaks coincide. Spatially: E ⊥ B ⊥ propagation.

Pattern 4 — Speed of EM Waves

• All EM waves travel at c = $3 \times 10^{8}$ m/s in vacuum regardless of frequency
• Common trap: "gamma rays travel faster because higher energy" — WRONG
• Strategy: c = 1/√(μ_{0}ε_{0}) — constant. Only differs in medium (dispersion).

Pattern 5 — X-ray vs Gamma Ray Distinction (NEET 2023 style)

• How to distinguish overlapping frequency ranges
• Strategy: Source-based: X-ray = electron deceleration/atomic; Gamma = nuclear decay.

High-Yield Topics (by frequency of appearance):

1. EM spectrum application matching — appears almost every year
2. Speed of EM waves in vacuum — 1–2 questions/year
3. Displacement current — every 2–3 years
4. E–B relationship and phase — every 2–3 years