Current Electricity Lab

Everywhere

• Topic tabs (under the title) switch between simulations in this lab. Some topics have smaller buttons under the stage for their screens.
• Teach shows live equations with the current numbers and "What to notice" points. Practice gives a numeric problem and a quiz.
• Move the sliders or tap the chips in the right-hand panel. The readings box updates live.
• Pause / Restart control the animation. Clean view hides everything except the stage, for projecting or recording; press Esc to leave it.
• In Practice, type a number (e.g. 12.5 or 3.2e-10), press Check or Enter. Show it on the stage sets the simulation to that problem.
• Nothing is saved: scores reset when the page is reloaded.

Language

• Choose English or বাংলা once on the home page (top right); every lab then opens in that language — tabs, controls, readings, equations, notes, problems and quizzes.

Current & Ohm's law

• Drift of electrons: electrons jittering through the lattice with a slow average drift; I = nAve and the drift speed for the current and wire you set.
• V–I graphs: a metal resistor, a filament lamp, a diode and a thermistor — which are ohmic and why.
• Resistance & resistivity: R = ρL/A for copper, aluminium, tungsten, nichrome and carbon, the R–T line R = R₀(1 + αΔT) and the resistivity bars.

Series & parallel

• Series: three resistors and a battery with the same current everywhere and the voltages adding up.
• Parallel: the same voltage across each branch and the currents adding; 1/R = 1/R₁ + 1/R₂ + 1/R₃.
• A mixed network: R₂ ∥ R₃ in series with R₁, reduced step by step.

EMF & Kirchhoff

• Internal resistance: a real cell with r inside, the ammeter and voltmeter, V = E − Ir and the V–I line (intercept E, slope −r).
• Power transfer: P against external R, maximum at R = r, P max = E²/4r and the efficiency.
• Kirchhoff's laws: two cells and three resistors solved live; a negative current shows the cell being charged.

Bridge & potentiometer

• Wheatstone bridge: set P, Q, R, S and watch the galvanometer; balance when P/Q = R/S.
• Meter bridge: known R, unknown X and a jockey on a 100 cm wire; X = R(100 − l)/l at balance.
• Potentiometer: a driver cell across the wire, two test cells, balancing lengths and E₁/E₂ = l₁/l₂.

Power & meters

• Power, heating & bills: pick an appliance, hours per day and tariff; I = P/V, R = V²/P, the kWh meter and the monthly cost.
• Galvanometer → ammeter: the shunt S = I_gG/(I − I_g) and how the current divides.
• Galvanometer → voltmeter: the multiplier R = V/I_g − G and the ohms-per-volt sensitivity.

Full guide with teaching tips: User manual (also as a PDF).