Current Electricity
Drift velocity, Ohm’s law, resistivity, temperature coefficient of resistance, internal resistance, Kirchhoff’s circuit laws, potentiometer, Wheatstone bridge, electromagnetic induction, motional EMF, AC circuits, and transformers.
Current Electricity — Lessons (10)
Electric Current & Drift Velocity
Electric current definition I = ΔQ/Δt, mobile charge carriers across metals, semiconductors, and electrolytes, microscopic drift velocity derivation I = nAv_de, and current density J = I/A.
Resistance, Resistivity & Temperature
Ohm’s law V = IR, resistance geometry R = ρl/A, electrical conductivity σ = 1/ρ, temperature coefficient of resistance R_θ = R₀(1 + αΔθ), ohmic vs non-ohmic components, and resistor color coding.
EMF, Internal Resistance & Power
Electromotive force (EMF) E = W/Q, internal resistance r, terminal potential difference V = E - Ir (discharge) and V = E + Ir (charging), V-I graphical determination of E and r, electrical power dissipation P = VI, and the Maximum Power Transfer Theorem.
Kirchhoff’s Laws & Networks
Equivalent series and parallel resistance formulas, Kirchhoff’s First Law (Current Law / Junction Rule, ΣI = 0), Kirchhoff’s Second Law (Voltage Law / Loop Rule, ΣE = ΣIR), and systematic mesh analysis of multi-loop DC networks.
Potentiometer & Bridge Circuits
Potential divider principle, uniform potentiometer wire and potential gradient k = V/l, comparison of cell EMFs (E₁/E₂ = l₁/l₂), cell internal resistance determination r = R(l₀ - l)/l, Wheatstone Bridge balance condition P/Q = R/S, and the Meter Bridge.
Electromagnetic Induction & Motional EMF
Magnetic flux linkage λ = NΦ, Faraday’s Law of Electromagnetic Induction ε = -N(dΦ/dt), Lenz’s Law and energy conservation, motional electromotive force on sliding conductors ε = Blv, and eddy current generation and damping.
Alternating Current (AC) & Transformers
AC generation principles, sinusoidal voltage V(t) = V₀ sin(ωt), Root-Mean-Square (RMS) definitions V_rms = V₀/√2 and I_rms = I₀/√2, transformer action V_s/V_p = N_s/N_p, step-up/step-down conversions, efficiency η, and transformer power losses.
DC Circuit & Transformer Simulation Lab
60fps interactive laboratory featuring a precision potentiometer null-balance experiment (investigating potential gradient and determining internal resistance) and an AC transformer power analyzer with real core lamination losses.
Unit 8 Comprehensive Assessment
20-question summative exam covering all 6 syllabus competencies (8.1 to 8.6) with automated grading, competency breakdown, and targeted revision links.
Current Electricity Practicals Hub
Complete suite of syllabus practicals: Exp 30 (V-I characteristics of conductor/diode), Exp 31 (internal resistance by voltmeter-ammeter), Exp 32 (resistance & resistivity by Meter Bridge), Exp 33 (temperature coefficient of resistance by Meter Bridge), Exp 34 (comparison of EMFs by Potentiometer), and Exp 35 (internal resistance of a cell by Potentiometer).