Trap 1 — Speed and Frequency Confusion All EM waves travel at c = m/s in vacuum regardless of frequency. Gamma rays do NOT travel faster than radio waves. Higher frequency means higher photon energy (E = hf) but NOT higher wave speed. In a medium, speed varies by wavelength (dispersion), but never in vacuum.
Trap 2 — Displacement Current = Real Current Displacement current is NOT electron flow. Id = ε_{0}(dΦ_E/dt) is produced by a changing electric field in the capacitor gap. No charge crosses the gap. However, it produces a magnetic field exactly as a real current would, and it equals the conduction current in the external circuit.
Trap 3 — E and B Out of Phase E and B fields in an EM wave are spatially perpendicular (point in different directions) but temporally in phase (oscillate together). They reach peaks, zeros, and troughs at the same instant. Confusing spatial orientation with temporal phase is a NEET trap.
Trap 4 — X-ray vs Gamma Classification by Frequency Stating that a frequency of 10^{19} Hz is "definitely X-ray" or "definitely gamma ray" is wrong. The ranges overlap (10^{18}–10^{21} Hz). Classification is source-based: Coolidge tube electrons → X-ray; radioactive nucleus → gamma ray.
Trap 5 — Application Mix-ups UV for sterilisation (NOT gamma). IR for physiotherapy (NOT UV). X-rays for bone imaging (NOT gamma). Gamma for cancer treatment. Microwaves for RADAR (NOT radio waves). These specific pairings are tested annually.
Trap 6 — Intensity Scaling Intensity ∝ (not ). Doubling the electric field amplitude quadruples the intensity. This is the square-law relationship from I = (1/2)ε_{0}c.