Semiconductors

🟢 Lite — Quick Review (1h–1d)

Rapid summary for last-minute revision before your exam.

EMI and AC — Key Facts Faraday’s Law: ε = -dΦ/dt; induced emf proportional to rate of change of magnetic flux Lenz’s Law: direction of induced current opposes the change causing it (conservation of energy) Self-induction: ε = -L(dI/dt); L depends on coil geometry (solenoid: L = μ₀N²A/l) Transformer: V_s/V_p = N_s/N_p = I_p/I_s; step-up (N_s > N_p), step-down (N_s < N_p) ⚡ Exam tip: Lenz’s Law always confirms energy is conserved — induced current creates opposing B

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🟡 Standard — Regular Study (2d–2mo)

Standard content for students with a few days to months.

EMI and AC — NEET/JEE Study Guide Motional emf: ε = Bℓv (rod moving in uniform B perpendicular to v and ℓ); ε = Bℓv sinθ general AC generator: ε = ε₀ sin(ωt); ε₀ = NBAω sin(ωt) (peak value); ω = 2πf Inductive reactance: X_L = ωL = 2πfL; capacitive reactance: X_C = 1/(ωC) = 1/(2πfC) LC oscillation: natural frequency ω = 1/√(LC); analogy with spring-mass mechanical oscillator

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🔴 Extended — Deep Study (3mo+)

Comprehensive coverage for students on a longer study timeline.

EMI and AC — Comprehensive Notes Self-inductance of solenoid: L = μ₀N²A/l; energy stored in inductor: U = ½LI² Mutual induction: M = k√(L₁L₂); ε₂ = -M(dI₁/dt); transformer efficiency ≈ 100% with ideal conditions AC through R, L, C: impedance Z = √(R² + (X_L - X_C)²); tan φ = (X_L - X_C)/R Power in AC: P_avg = V_rms I_rms cosφ; cosφ = power factor; for pure resistance cosφ=1, for pure L or C cosφ=0 Sharpness of resonance: Q = ω₀L/R = 1/(ω₀CR); high Q → narrow resonance peak

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