Chapter 05WBCHSE BoardClass XIIPhysics
Electromagnetic Induction & Alternating Current
তড়িচ্চৌম্বকীয় আবেশ ও পরিবর্তী প্রবাহ
Faraday's laws, Lenz's rule, motional EMF, eddy currents, self and mutual inductance, AC generation, phasor diagrams, and series LCR resonance.
0 Core Topics
1 Study Materials
Syllabus Reference Module
Target Learning Objectives
- State Faraday's laws of induction and apply Lenz's law for induced current directions.
- Derive motional EMF (E = Bvl) and self/mutual inductance coefficients.
- Construct phasor diagrams for pure and combined AC circuits (R, L, C, and LCR).
- Calculate resonant frequency, quality factor (Q-factor), and power factor in AC circuits.
Governing Physical Concepts
- Magnetic Flux & Faraday's Law (ε = -dΦ_B/dt)
- Motional EMF & Eddy Currents
- Self Inductance (L) & Mutual Inductance (M)
- AC Waveforms: Peak, Mean & RMS Values (V_rms = V0 / sqrt(2))
- Series LCR Circuit: Impedance Z = sqrt(R^2 + (X_L - X_C)^2)
- Resonant Frequency (ω0 = 1 / sqrt(LC)) & Power Factor (cos φ)
- Transformer Equation & Efficiency (Vs/Vp = Ns/Np = Ip/Is)
Structured Concept Hierarchy
Chapter Topics & Breakdown
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REVISIONv2026.1 • BILINGUAL
EMI & AC Circuits: Spaced Retention Revision Digest
High-yield revision digest breaking down Faraday's laws, motional EMF, phasor diagrams for LCR circuits, resonance condition, and transformer power loss.
6 PagesOpen Resource
Quick Revision Summary
“In a pure inductor, current lags voltage by π/2; in a pure capacitor, current leads voltage by π/2.”
- •Lenz's law is an immediate consequence of the law of conservation of energy.
- •At resonance in series LCR: impedance Z is minimum (Z = R), current is maximum, and power factor is unity (cos φ = 1).
- •Average power in AC circuit: P_avg = V_rms I_rms cos φ.
Structured Practice Roadmap
Numericals covering AC resonance, transformer calculations, and flux derivative inductions.
Problem Bank Volume:30 Selected Problems
Problem Categories:
LCR Phasor AnalysisTransformer EfficiencyInductive EMF
Board Diagnostic 05: EMI & AC
Assessment Architecture • Academic Evaluation SpecificationComprehensive written paper on alternating currents and induction.
FormatWritten Board Paper
Duration75 Minutes
CoverageStructured Assessment
* Note: Written assessments are administered and reviewed directly by faculty. Digital diagnostic assessment engines are scheduled for subsequent platform phases.